Search

Los escarabajos gigantes de la tribu Dynastini (Coleoptera: Melolonthidae) reúnen en Colombia tres géneros y 14 especies. Megasoma Kirby o escarabajos elefante, está representado por cuatro especies; no obstante, lo carismáticas y famosas, han permanecido poco exploradas en su biología, por lo que esta investigación se propuso describir los estados inmaduros y realizar los ciclos de vida de Megasoma actaeon, M. elephas y M. janus ramirezorum en Colombia. En el marco de varios proyectos institucionales, se confinaron parentales de las tres especies en diferentes momentos (1998-2012 y 2017-2019), implementando protocolos de cría, en un laboratorio de bioensayos (Palmira, Valle, 24o C, 980 msnm); la toma de datos se realizó cada quince días e incluyó información sobre ancho de cabeza, ancho a nivel del tórax y longitud corporal; en el proceso algunos ejemplares fueron fijados para el estudio decaracteres larvales, descripción, fotografía y elaboración de artes gráficos; los ciclos de vida de las tres especies se desarrollaron de huevo a adulto, compilándose en tablas los datos de los tiempos y medidas de crecimiento de los estados de huevo, L1, L2, L3, prepupa, pupa y adultos; los resultados evidenciaron ciclos de vida muy largos, de varios años: Megasoma actaeon 3.2-3.3 años, M. elephas 2.4-2.6 años y M. janus ramirezorum 3.1-3.2 años; las larvas de tercer instar (L3), pupas macho y hembra fueron descritas e ilustradas, presentándose las claves taxonómicas respectivas. En cuanto a la morfología larval, la redescripción de M. actaeon discrepó (maxila con 4-5 dientes estriduladores), M. elephas fue más coincidente (con diferencias menores en la quetotaxia cefálica y del dorsum del segmento abdominal I, quizás por razones geográficas), mientras que M. janus ramirezorum se describe por primera vez y se incorporó a la clave en el grupo de especies grandes con 4-5 dientes estriduladores en la maxila, ancho cefálico entre 11-18 mm, con el diámetro de los espiráculos abdominales agrandados progresivamente y bulla poco convexa, casi vertical. Finalmente, se deja como recomendación continuar las investigaciones en estas especies de supervivencia frágil, dados los ciclos de vida muy largos y la intensa deforestación de su hábitat.

Hydrophobic molecules are by definition difficult to hydrate. Previous studies in the area of hydrophobic hydration have therefore often relied on using amphiphilic molecules where the hydrophilic part of a molecule enabled the solubility in liquid water. Here we show that the hydrophobic adamantane (C10H16) molecule can be fully hydrated through vapour codeposition with water onto a cryogenic substrate at 80 K resulting in the matrix isolation of adamantane in amorphous ice. Using neutron diffraction in combination with the isotopic substitution method and the empirical potential structure refinement technique, we find that the first hydration shell of adamantane is well structured consisting of a hydrogen-bonded cage of 28 water molecules that is also found in cubic structure II clathrate hydrates. The four hexagonal faces of the 51264 cage are situated above the four methine (CH) groups of adamantane whereas the methylene (CH2) groups are positioned below the edges of two adjoining pentagonal faces. The oxygen atoms of the 28 water molecules can be categorised on the basis of symmetry equivalences as twelve A, twelve B and four C oxygens. The water molecules of the first hydration shell display orientations consistent with those expected for a clathrate-hydrate-type cage, but also unfavourable ones with respect to the hydrogen bonding between the water molecules. Annealing the samples at 140 K, which is just below the crystallisation temperature of the matrix, removes the unfavourable orientations and leads to a slight increase of the structural order of the first hydration shell. The very closest water molecules display a tendency for their dipole moments to point towards the adamantane which is attributed to steric effects. Other than this, no significant polarisation effects are observed which is consistent with weak interactions between adamantane and the amorphous ice matrix. FT-IR spectroscopy shows that the incorporation of adamantane into amorphous ice leads to a weakening of the hydrogen bonds. In summary, the matrix-isolation of the highly symmetric adamantane in amorphous ice provides an interesting test case for hydrophobic hydration. Studying the structure and spectroscopic properties of water at the interface with hydrophobic hydrocarbons is also relevant for astrophysical environments, such as comets or the interstellar medium, where amorphous ice and hydrocarbons have been shown to coexist in large quantities.

Colombia contiene una notable diversidad de escarabajos longicornios (Coleoptera: Cerambycidae), una inmensa familia de la cual incluye en su geografía grupos emblemáticos como son los longicornios de los géneros Chalcoprionus Bates, 1875 (Macrodontiini) y Braderochus Buquet, 1852 (Prionini), los cuales resaltan por su rareza en las colecciones nacionales y por lo fraccionario de sus registros geográficos, razón por la cual esta investigación se propuso aportar nuevos datos sobre la distribución de las especies colombianas. La metodología articuló revisión de literatura y de algunos ejemplares de colecciones nacionales (la del autor CFPL-COL y la del Museo de Historia Natural-HN Universidad de Caldas). Sobre Chalcoprionus badeni Bates 1875, se ilustra por primera vez el macho, junto a la hembra; se registran datos de tres ejemplares colectados en selvas muy húmedas de la quebrada La Cristalina, cuenca Calima (1400-1600 msnm), municipio de Darién, Cordillera Occidental, Valle del Cauca, discutiendo además los registros originales en Antioquia y la prioridad de conservación de esta magnífica especie; Braderochus, estuvo representada por cuatro especies así: B. dentipes (Chemsak, 1979) (Chocó), B. hovorei (Santos-Silva & Martins, 2005) (Antioquia, Cundinamarca, Boyacá, Santander), B. levoiturieri (Buquet, 1842) (Caldas, Boyacá, Santander) y B. retrospinosus (Lameere, 1916) (Meta, Caquetá); los nuevos datos, además de novedosos, reiteran un precario estado de conocimiento y un mapa de distribución muy relictual, estimándose en la mayoría de las especies una expectativa de supervivencia bastante incierta. La conservación de todas estas notables y endémicas especies, incluidas entre los pilares de la genealogía de los Prioninae neotropicales, se constituye en un aspecto prioritario, que debe articular el estudio, establecimiento y manejo de áreas de conservación.

Pardo-Locarno, Luis Carlos, Constantino, Luis Miguel (2023): Una nueva especie de Alurnus Fabricius de la costa pacífica de Colombia y apuntes sobre su biología (Coleoptera: Chrysomelidae: Cassidinae). Insecta Mundi 2023 (970): 1-8, DOI: http://doi.org/10.5281/zenodo.7887588, {"references":["Constantino LM, Pardo-Locarno LC, Agudelo R, Caicedo-Sinisterra H, Torres- Campaz A. 2021. Manejo integrado de los barrenadores del fruto (Palmelampius heinrichi y Parisoschoenus bactrisae) de chontaduro (Bactris gasipaes), en la Costa Pacifica de Colombia. Investigacion Agropecuaria 18(1): 12-38.","Fischer CR. 1935. Os Coleopteros phytophagos da tribu Alurnini, pragas das palmeiras (Chysomelidae, Hispinae). Revista de Entomologia 5: 257-292.","ICA. 1972-1974. Boletin notas y noticias entomologicas. Instituto Colombiano Agropecuario Tibaitata Programa de Entomologia; Mosquera, Colombia. 10 p.","IGAC. 1989. Suelos y bosques de Colombia. Instituto Geografico Agustin Codazzi; Bogota. 134 p.","Mena E. 1978. Observaciones sobre chontaduro en Tumaco. p. 41-42. En: Patino VM. El Chontaduro. Primera reunion sobre seleccion, cultivo e industrializacion del cachipay o chontaduro Bactris gasipaes HBK. Cali 26-27 de enero de 1978. Departamento del Valle del Cauca. Secretaria de Agricultura y Fomento. Seccion Divulgacion y Publicaciones. CONIF-Jardin Botanico del Valle-Instituto Matia Mulumba de Buenaventura; Cali, Colombia. 87 p.","Pardo-Locarno LC. 1992. Contribucion al estudio de los coleopteros de interes agricola y forestal en la cuenca calima - bajo San Juan (Valle-Choco) Colombia. Cespedesia 19(62-63): 47-85.","Pardo-Locarno LC, Constantino LM, Agudelo R, Alarcon A, Caicedo V. 2005. Observaciones sobre el gualapan (Coleoptera: Chrysomelidae: Hispinae) y otras limitantes entomologicas en cultivos de chontaduro (Bactris gasipaes H.B.K.) en el Bajo Anchicaya. Acta Agronomica (Colombia) 54(2): 25-31.","Pardo-Locarno LC, Constantino LM, Agudelo R, Caicedo B. 1997. Complejos entomologicos del chontaduro (Bactris gasipaes H.B.K.) en el Bajo Anchicaya, Valle. En: XXIV Congreso de la Sociedad Colombiana de Entomologia (SOCO- LEN). Pereira. Resumenes. 78 p.","Pardo-Locarno LC, Constantino LM, Bustillo AE. 2019. Fichas tecnicas sobre las plagas mas importantes en el cultivo de chontaduro en la zona rural de Buenaventura. p. 65-105. En: Pardo-Locarno LC (ed.). Manejo sostenible del cultivo de chontaduro en la costa Pacifico Colombiana. Secretaria de Agricultura y Pesca, Inciva, Gobernacion del Valle del Cauca, Universidad del Pacifico; Buenaventura, Colombia. 134 p.","Pardo-Locarno LC, Vallecilla H, Caicedo N. 2015. Manejo sostenible del cultivo de chontaduro en la Zona Rural de Buenaventura, Valle. Cartilla divulgativa. Septima convocatoria del Fondo Participativo para la Accion Ambiental-CVC. Convenio Asociacion Agroecologica Frutas del Pacifico-Corporacion Autonoma Regional-CVC; Buenaventura, Valle, Colombia. 35 p.","Posada L. 1989. Lista de insectos daninos y otras plagas en Colombia. Instituto Colombiano Agropecuario, Boletin Tecnico No. 43: 1-662.","Staines CL. 2002. The New World tribes and genera of hispines (Coleoptera: Chrysomelidae: Cassidinae). Proceedings of the Entomological Society of Washington 104(3): 721-784.","Staines CL. 2013. A review of the genus Alurnus Fabricius, 1775 (Coleoptera: Chrysomelidae: Cassidinae). Insecta Mundi 0291: 1-34."]}

Materials undergoing pressure-driven solid-solid phase transformations can be a valuable alternative for eco-friendly refrigeration, heat pumping and waste heat recovery based on the barocaloric effect. Ferroelectric compounds and plastic crystals...

Los escarabajos gigantes de la tribu Dynastini reúnen en Colombia tres géneros y 14 especies, de las cuales dos pertenecen al género Dynastes Kirby, 1825: D. hercules (Linné, 1758), que incluye tres subespecies y D. neptunus Quenzel, 1817, todas ellas representativas de la biodiversidad nacional. Sin embargo, hace falta mayor investigación en cuanto a los aspectos biológicos y ecológicos, razón por la cual, esta investigación se propuso desarrollar el ciclo de vida y describir la morfología larval de Dynastes hercules L. (D. h. lichyi Lachaume y D. h. occidentalis Lachaume) y de Dynastes neptunus Quenzel (Coleoptera: Melolonthidae: Dynastini), incluyendo un clave para larvas y pupas y discusión de los caracteres estudiados. La investigación se desarrolló en un laboratorio de bioensayos en Palmira (Valle del Cauca, Colombia. Para cada caso se utilizaron recipientes con sustrato orgánico esterilizado, larvas individualizadas, toma de datos de anchura cefálica, anchura corporal y longitud del cuerpo, cada quince días; las muestras fueron fijadas en solución de formol y se etiquetaron cuidadosamente. El ciclo de vida en los tres casos fue largo, alcanzando una media de 1.5-1.8 años, con una porción de casos que superó los dos años; en cuanto a la morfología larval el número de setas dorso epicraneales y la quetotaxia de los apéndices (tarsúngulo), de los teges, y de la acanthoparia se consideran, por ahora, focales en este género. La morfología larval expuso una gran similitud y afinidad entre las especies estudiadas, descartando por ahora erigir especies entre las subespecies de D. hercules. La morfología pupal fue bastante similar, evidenciándose solo sutiles diferencias en dos aspectos de la dorsa de los segmentos abdominales VII y VIII. Tanto en la morfología larval como en la de pupa se evidenció una mayor divergencia en Dynastes (Theogenes) neptunus Quenzel, algo que daría validez a este subgénero tan poco estudiado por los autores. Es recomendable ahondar en aspectos del ciclo biológico de D. neptunus dada la mayor duración del mismo, quizás afectado por la alta temperatura.

Many materials of interest and processes relevant to life are based in disordered phases. This disorder can be either positional, orientational or both as in the case of liquids. Unfortunately, the study of disordered phases is inherently difficult given the lack of periodicity as in ordered crystals. In this work we use neutron and X-ray diffraction experiments together with molecular dynamics simulations to study the local order and molecular movements in the disordered phases of hexachloroethane both in the liquid phase and in its plastic phase. The latter is a phase in which the molecular centres of mass form a long-range ordered crystalline lattice but molecules can rotate more or less freely. The concurrent use of diffraction experiments (Neutron and X-ray) and molecular dynamics simulations show that liquid structure mimics that of the disordered crystal at short distances. In order to extend the analysis to long distances, we have borrowed magnitudes from information theory that allow us to measure disorder and correlation. We also use the Kullback-Leibler divergence, an indicator of how similar two structures are to study the differences between plastic and liquid phases, as well as the structural difference at varying temperatures. We thus also offer in this work a common framework to characterize the structure of any disordered phase firmly based on probability and information theory. The advantage of our proposed methodology is that it can be used both to characterize the disorder and to perform comparisons of disordered materials with different degrees of freedom such as liquids and disordered crystals.

Objective. To establish the variation of the diversity, density and biomass of white grubs of the Melolonthidae family in soils affected by mining and in the soil of an oak forest in the upper basin of the Surata river (Santander, Colombia). Scope. To analyse the diversity, density and biomass of the immature stages of beetles (Coleoptera: Melolonthidae) on two soil uses: recovered gold exploration platforms and an oak forest. Methodology. Monthly quadrants of 1 m2 by 30 cm deep were made throughout 12 months of sampling. The area of study is located in the northeast Colombian Andes, between 2,300 and 2,950 meters above sea level. Correlations were established between the measured parameters (abundance, richness of species, biomass, density and numbers of Hill) and biophysical factors of the study area. Main results. The highest values were observed in the oak forest: 12 species, 6.16 gr/m2 and density 4.08 ind./m2. However, only the biomass values were statistically significant (Z = 2.903; p = 0.004). Significant correlations were observed between abundance, density and biomass with the lowest humidity in the platforms but not in the oak forest. The maximum values of abundance, density and biomass coincided with the rainy season, and the highest values of diversity occur at the end of the dry seasons. Conclusions. The data obtained in this high mountain ecosystem show interesting variations in abundance and richness, which can be explained by the presence of a wide and extensive matrix of oak forest that allows the permanence of species of white grubs and relatively well-preserved natural populations. Resumen Objetivo. Establecer la variación de la diversidad, densidad y biomasa de las chisas de la familia Melolonthidae en suelos afectados por minería y en suelo de un bosque de roble en la cuenca alta del río Suratá (Santander, Colombia). Alcance. Analizar diversidad, densidad y biomasa de los estados inmaduros de escarabajos (Coleoptera: Melolonthidae) en dos usos del suelo: plaformas de exploración aurífera recuperadas y un robledal. Metodología. A lo largo de 12 meses de muestreo se realizaron cuadrantes mensuales de 1 m2 por 30 cm de profundidad. El área de estudio se localiza en el nororiente de los Andes colombianos, entre los 2.300 y 2.950 msnm. Se establecieron correlaciones entre los parámetros medidos (abundancia, riqueza de especies, biomasa, densidad y números de Hill) y los factores biofísicos de la zona de estudio. Resultados principales. Los mayores valores fueron observados en el robledal: riqueza 12 especies, biomasa 6,16 gr/m2 y densidad 4,08 ind./m2. Sin embargo, solo los valores de biomasa fueron estadísticamente significativos (Z = 2,903; p = 0,004). Se observaron correlaciones significativas entre abundancia, densidad y biomasa con la húmedad más baja en las plataformas pero no en el robledal. Los valores máximos de abundancia, densidad y biomasa coinciden con las temporadas de lluvia y los mayores valores de diversidad ocurren al final de las temporadas secas. Conclusiones. Los datos obtenidos en este ecosistema de alta montaña presentan interesantes variaciones de abundancia y riqueza, lo cual puede ser explicado por la presencia de una amplia y extensa matriz de bosque de roble que permiten la permanencia de especies de chisas y poblaciones naturales relativamente bien conservadas.

Objective: To describe two new species of the genus Golofa. Scope: To expand the list of species of the tribe Dynastini for Colombia. Methodology: We reviewed the specimens of the genus Golofa deposited in the Colección Familia Pardo-Locarno CFPL-COL, establishing differences between the species already identified and the specimens type used for the description of the two new species reviewed in this manuscript. Main results: We described two new species of Golofa Hope, 1837, showing photographic records with diagnostic value. The number of species for Colombia is increased to nine, thus, the synopsis of species is formed as follows: Golofa aegeon Drury, 1773, Golofa antiqua Arrow, 1911, Golofa claviger Linnaeus, 1771, Golofa eacus Burmeister, 1847, Golofa paradoxa Dechambre, 1975, Golofa pelagon Burmeister, 1847, Golofa porteri Hope, 1837, Golofa farallonensis n. sp. Pardo-Locarno & Villalobos-Moreno y Golofa veliae n. sp. Pardo-Locarno & Villalobos-Moreno. Conclusions: These records ratify the Tropandean distribution of the group, evidencing the little biological and biogeographic knowledge of this group in Colombia. The results indicate a great diversity of the genus in the country, so that, the study of species distribution is recommended. Resumen Objetivo: Realizar la descripción de dos nuevas especies del género Golofa. Alcance: Ampliar el listado de especies de la tribu Dynastini para Colombia. Metodología: Se revisaron los especímenes del género Golofa depositados en la Colección Familia Pardo-Locarno CFPL-COL, estableciéndose diferencias entre las especies ya identificadas y los ejemplares tipo usados para la descripción de las dos nuevas especies que se revisan en el presente manuscrito. Principales resultados: Se describen dos nuevas especie de Golofa Hope, 1837, presentándose registros fotográficos con valor diagnóstico. Se amplía a nueve el número de especies para Colombia, quedando la sinopsis de especies conformada así: Golofa aegeon Drury, 1773, Golofa antiqua Arrow, 1911, Golofa claviger Linnaeus, 1771, Golofa eacus Burmeister, 1847, Golofa paradoxa Dechambre, 1975, Golofa pelagon Burmeister, 1847, Golofa porteri Hope, 1837, Golofa farallonensis n. sp. Pardo-Locarno & Villalobos-Moreno y Golofa veliae n. sp. Pardo-Locarno & Villalobos-Moreno. Conclusiones: Estos registros ratifican la distribución tropandina del grupo, evidenciándose el poco conocimiento biológico y biogeográfico de este grupo en Colombia. Los resultados indican una gran diversidad del género en el país. Se recomienda ampliar el estudio de la distribución de las especies mencionadas.

Water has a rich phase diagram with several crystals, as confirmed by experiments. High-pressure and high-temperature water is of interest for Earth’s mantle and exoplanetary investigations. It is in this region of the phase diagram of water that new plastic crystal phases of water have been revealed via computer simulations by both classical forcefields and ab initio calculations. However, these plastic phases still remain elusive in experiments. Here, we present a complete characterization of the structure, dynamics, and thermodynamics of the computational plastic crystal phases of water using molecular dynamics and the two-phase thermodynamic method and uncover the interplay between them. The relaxation times of different reorientational correlation functions are obtained for the hypothetical body-centered-cubic and face-centered-cubic plastic crystal phases of water at T = 440 K and P = 8 GPa. Results are compared to a high pressure liquid and ice VII phases to improve the understanding of the plastic crystal phases. Entropy results indicate that the fcc crystal is more stable compared to the bcc structure under the studied conditions.

The amino acid lysine has been shown to prevent water crystallization at low temperatures in saturated aqueous solutions [S. Cerveny and J. Swenson, Phys. Chem. Chem. Phys., 2014, 16, 22382–22390]. Here, we investigate two ratios of water and lysine (5.4 water molecules per lysine (saturated) and 11 water molecules per lysine) by means of the complementary use of computer simulations and neutron diffraction. By performing a detailed structural analysis we have been able to explain the anti-freeze properties of lysine by the strong hydrogen bond interactions of interstitial water molecules with lysine that prevent them from forming crystalline seeds. Additional water molecules beyond the 1 : 5.4 proportion are no longer tightly bonded to lysine and therefore are free to form crystals., This work was supported by the Spanish Ministry of Science and Innovation through the project FIS2014-54734-P, MINECO (grants FIS2015-66879-C2-1-P, FIS2017-82625-P and PID2019-104650GB-C21) and by the Generalitat de Catalunya under the projects 2014-SGR-581 and 2017-SGR-042. The UK Science and Technology Facilities Council is gratefully acknowledged for partial financial support and beam time access at the ISIS Facility (RB1220294). A. Henao would like to thank the Thomas Young Centre for the Junior research fellowship supporting a stay with C. D. Lorenz. S. Cerveny thanks CSIC (LINKB20012).

In his comment on a recent publication by us, G. Graziano claims that solubility differences of indole in methanol and water can be rationalized by the reversible work needed to create a cavity in the solvent of the size of the solute, in this case indole. This quantity, he argues, is closely related to the solvent accessible surface area, which is greater for methanol compared with water, thus making indole more soluble in the former solvent. G. Graziano asserts that it is this property which is responsible for the large difference between the solubilities of indole in methanol and water. Further, G. Graziano claims that the differences in excess entropies and in distance distribution functions of indole in methanol and water and in methanol and water as a cosolvent found in our original work (Henao, et al., Phys. Chem. Chem. Phys., 2016, 18, 23006) are too “small” to be able to account for the differences in solubility of the indole molecule. We show in this work that the differences found by us are not small, by displaying some selected distance distribution functions in an alternative way to that described in our original paper. In fact we conclude that the differences in these functions are quantitatively greater than those found by Graziano in his comment. Secondly, we show in this reply that although the increase of the solvent accessible surface area may rationalize the differences in the indole–methanol and indole–water binary systems, and thus the work required for cavity creation, it is insufficient to fully account for the increase of indole solubility in water by the addition of very small quantities of methanol in the ternary system indole–methanol–water. In other words, as stated in our original paper, methanol is actively changing the solvation shell and not just passively increasing the solvent accessible surface area around indole. As a result of these additional analyses, we conclude that our work on the solvation differences of indole in water and methanol successfully captures differences in the solvation shells of both solvents around indole in both binary and ternary systems. Finally, while we do agree that Graziano's calculations are able to capture the role of cavity creation to explain differences in solubility, we think that our results concerning the quantification of changes in molecular interaction should be added to the calculations suggested by him to lead to a full description of the solubility.

En Colombia, los escarabajos del géneroSphaenognathus(Coleoptera: Lucanidae: Chiasognathini) conforman un linaje eminentemente tropandino, de selvas frías, razón por la cual su distribución exhibe un patrón insular muy complejo, poco conocido y que se ve agravado por la falta de estudios para conocer su ecología y distribución y la acelerada destrucción de dichos hábitats. Esta investigación se propuso re describir a la especieS. rotundatusLacroix y adicionar registros geográficos sobreS. prionoidesBuquet. Los ejemplares estudiados fueron recolectados en proyectos de investigación de biodiversidad del Páramo de Santurbán (California, Santander, Colombia). Los datos sugieren la validez taxonómica deS. rotundatusy lo registran por primera vez para Colombia; así mismo, se plantea el registro deS. prionoidescomo propio de la Cordillera Oriental colombiana en los departamentos de Cundinamarca, Boyacá y Santander. Beetles of the genusSphaenognathus(Coleoptera: Lucanidae: Chiasognathini) in Colombia, form an eminently tropandean lineage of cold jungles, reason why its distribution shows a very complex insular pattern, little known and that is aggravated by the lack of studies to learn about its ecology and distribution, and the accelerated destruction of such habitats. This research was proposed to redescribe the speciesS. rotundatusLacroix and to add geographical records ofS. prionoidesBuquet. The specimens studied were collected in biodiversity research projects in the Santurban Moor (California, Santander, Colombia). The data suggest the taxonomic validity ofS. rotundatusand record it for the first time for Colombia. Likewise, the record ofS. Prionoidesas typical of the Colombian Eastern Mountain Range on the departments of Cundinamarca, Boyacá and Santander is suggested.

Publicaciones seriadas

9 pags. 5 figs., Both structural glasses and disordered crystals are known to exhibit anomalous thermal, vibrational, and acoustic properties at low temperatures or low energies, what is still a matter of lively debate. To shed light on this issue, we studied the halomethane family CBrnCl4-n (n=0,1,2) at low temperature where, despite being perfectly translationally ordered stable monoclinic crystals, glassy dynamical features had been reported from experiments and molecular dynamics simulations. For n=1,2 dynamic disorder originates by the random occupancy of the same lattice sites by either Cl or Br atoms, but not for the ideal reference case of CCl4. Measurements of the low-temperature specific heat (Cp) for all these materials are here reported, which provide evidence of the presence of a broad peak in Debye-reduced Cp(T)/T3 and in the reduced density of states (g(ω)/ω2) determined by means of neutron spectroscopy, as well as a linear term in Cp usually ascribed in glasses to two-level systems in addition to the cubic term expected for a fully ordered crystal. Being CCl4 a fully ordered crystal, we also performed density functional theory (DFT) calculations, which provide unprecedented detailed information about the microscopic nature of vibrations responsible for that broad peak, much alike the >'boson peak> of glasses, finding it to essentially arise from a piling up (at around 3-4 meV) of low-energy optical modes together with acoustic modes near the Brillouin-zone limits., The authors are grateful for the financial support received within Projects No. FIS2017-82625-P and No. FIS2017- 84330-R from MINECO. We also acknowledge the Generalitat de Catalunya under Project No. 2017SGR-042 and the Autonomous Community of Madrid through program NANOFRONTMAG-CM (S2013/MIT-2850). One of us (M.A.R.) also acknowledges the “María de Maeztu” Program for Units of Excellence in R&D (MDM-2014-0377). The authors gratefully acknowledge the Science & Technology Facilities Council for financial support for this project, including personnel training and visits to the ISIS Molecular Spectroscopy Group, access to beam time at the ISIS Facility (RB910454, RB1320105), as well as computing resources from the STFC Scientific Computing Department’s SCARF cluster.

In glass-forming substances, the addition of water tends to produce the effect of lowering the glass transition temperature, T. In a previous work by some of us (Ruiz et al., Sci. Rep., 2017, 7, 7470) we reported on a rare anti-plasticizing effect of water on the molecular dynamics of a simple molecular system, the pharmaceutically active prilocaine molecule, for which the addition of water leads to an increase of T. In the present work, we study pure and hydrated prilocaine confined in 0.5 nm and 1 nm pore size molecular sieves, and carry out a comparison with the bulk compounds in order to gain a better understanding of the microscopic mechanisms that result in this rare effect. We find that the T of the drug under nanometric confinement can be lower than the bulk value by as much as 17 K. Through the concurrent use of differential scanning calorimetry and broadband dielectric spectroscopy we are able to observe the antiplasticizing effect of water in prilocaine also under nanometric confinement, finding an increase of T of up to almost 6 K upon hydration. The extension of our analysis to nanoconfined systems provides a plausible explanation for the very uncommon antiplasticizing effect, based on the formation of water-prilocaine molecular complexes. Moreover, this study deepens the understanding of the behavior of drugs under confinement, which is of relevance not only from a fundamental point of view, but also for practical applications such as drug delivery., This work has been partially supported by the Spanish Ministry of Economy and Competitiveness MINECO through project FIS2017-82625-P and through the project MAT2015-69547-R, and by the Generalitat de Catalunya under project 2017SGR-42. We also thanks Elkartek program (nG17, KK-2017/00012) and the Bask Government under project IT-1175-19

The Small Dung Beetles (Coleoptera: Scarabaeidae: Aphodiinae), mostly saprophagous habits, are a group of wide global distribution, relatively diverse in the tropics, although they are little known and studied for their cryptic habits and complex taxonomy. Given the above and with a view to promoting its study, this research was proposed, inventory the Colombian species and provide taxonomic keys of the records found in the literature of the group. For the first case (catalog), multiple bibliographic sources were consulted, to a lesser degree some species and records were studied in the collection of the first author (Colección Familia Pardo-Locarno-CFPL-COL). Followed by the above, a taxonomic key was elaborated. The results covered 20 genera and 56 species of Aphodiinae for Colombia, providing a key at the level of tribes, genera and species. These results allow us to infer that the group could be poorly sampled and, therefore, be much more diverse than what is noted here, it is also expected that new studies will specify the distribution maps of the species, which are now very fragmentary. Resumen Los escarabajos Aphodiinae (Coleoptera: Scarabaeidae), en su mayoría de hábitos saprófagos, constituyen un grupo de amplia distribución mundial; relativamente diverso en los trópicos, pero poco conocido y estudiado por sus hábitos crípticos y su compleja taxonomía. Objetivo: Inventariar las especies colombianas y aportar claves taxonómicas de los registros encontrados en la literatura del grupo. Metodología: Para el primer caso (catálogo) fueron consultadas múltiples fuentes bibliográficas, en menor grado algunas especies y registros fueron estudiados en la colección del primer autor (Colección Familia Pardo-LocarnoCFPL-COL). Posteríormente se elaboró una clave taxonómica. Resultados: Los resultados abarcaron 20 géneros y 56 especies de Aphodiinae para Colombia; aportando una clave a nivel de tribus, géneros y especies. Conclusiones: Los resultados permiten inferir que el grupo podría estar poco muestreado y por lo mismo, ser mucho más diverso de lo que aquí se anota; igualmente se espera que nuevos estudios precisen los mapas de distribución de las especies, los cuales ahora se observan muy fragmentaríos.

Although they are both highly polar liquids, there are a number of compounds, such as many pharmaceuticals, which show vastly different solubilities in methanol compared with water. From theories of the hydrophobic effect, it might be predicted that this enhanced solubility is due to association between drugs and the less polar -CH3 groups on methanol. In this work, detailed analysis on the atomic structural interactions between water, methanol and the small molecule indole - which is a precursor to many drugs and is sparingly soluble in water yet highly soluble in methanol - reveal that indole preferentially interacts with both water and methanol via electrostatic interactions rather than with direction interactions to the -CH3 groups. The presence of methanol hydrogen bonds with π electrons of the benzene ring of indole can explain the increase in solubility of indole in methanol relative to water. In addition, the excess entropy calculations performed here suggest that this solvation is enthalpically rather than entropically driven.

The microscopic structure of the tryptophan side chain, indole, in an amphiphilic environment has been investigated using a combination of neutron diffraction measurements and simulations in solution. The results show that indole is preferentially solvated by hydrogen bonding interactions between water and alcohol -OH groups rather than the interaction being dominated by indole-methyl interactions. This has implications for understanding how tryptophan interacts with the amphipathic membrane environment to anchor proteins into membranes, where the results here suggest that the benzene ring of tryptophan interacts directly with the interfacial water at the membrane surface rather than being buried into the hydrophobic regions of the membrane bilayer.

Objetivo: Realizar análisis sobre la estacionalidad de la familia Melolonthidae en un robledal aledaño al Parque Natural Regional Páramo de Santurbán, municipio de California, Santander, Colombia, del mismo modo, explorar el comportamiento de los gremios alimenticios encontrados en los muestreos. Alcance: Contrastar el hecho de que los Melolonthidae (y los diferentes gremios) sufren variaciones anuales que, en cierto modo, pueden estar relacionadas con diversos factores estacionales o ambientales. Metodología: Se usaron trampas de luz, carpotrampas con fruta y colecta manual dentro de un robledal aledaño al Parque Natural Regional Paramo de Santurbán, municipio de California, Santander, Colombia. Se realizaron análisis sobre la estacionalidad de los escarabajos de la familia Melolonthidae (Coleoptera: Scarabaeoidea), así como de los gremios alimenticios encontrados, mediante el uso de análisis multivariados (GLM) para establecer la correlación entre ellos, la familia, y los factores estacionales y biofísicos de la zona de estudio. Principales resultados: Se capturaron 1.152 ejemplares de la familia Melolonthidae pertenecientes a 16 géneros y 26 especies. Para la familia Melolonthidae, el promedio de temperaturas mínimas (tm), la precipitación acumulada (P) y la precipitación media (Pmed) explican un alto porcentaje de la variación tanto de la abundancia como de la riqueza de especies. Conclusiones: Los análisis estadísticos no muestran un efecto claro entre los factores que podrían influir sobre la riqueza y abundancia de los diferentes gremios alimenticios de Melolonthidae encontrados para la zona de estudio. A partir de los resultados obtenidos, el presente estudio abre la puerta a la exploración de los efectos causales destacados en los análisis, que podrían tener una gran importancia para la biodiversidad de los diferentes gremios de escarabajos Melolonthidae. Objective: To perform analyses on the seasonality of the Melolonthidae family in an oak grove adjacent to the Paramo de Santurbán Regional Natural Park, municipality of California, Santander, Colombia, as well as to explore the behavior of the food guilds found in the samplings. Scope: To contrast the fact that the Melolonthidae (and the different guilds) present annual variations that, in a certain way, can be related to several seasonal or environmental factors. Methodology: Light traps, fruit-traps and manual collection were used in an oak grove adjacent to the Paramo de Santurbán Regional Natural Park, municipality of California, Santander, Colombia. Analysis of the seasonality of beetles of the Melolonthidae (Coleoptera: Scarabaeoidea) family, as well as the food guilds, were carried out using multivariate analyses (GLM) to establish the correlation between them, the family, and the seasonal and biophysical factors in the study area. Main results: A total of 1,152 specimens of the Melolonthidae family, belonging to 16 genera and 26 species, were captured. The average minimum temperatures (mt), accumulated precipitation (P) and mean precipitation (medP) explain a high percentage of the variation of both abundance and species richness for the Melolonthidae family. Conclusions: The statistical analyses do not show a clear effect between the factors that could influence the richness and abundance of the different food guilds of Melolonthidae found for the study area. Based on the results obtained, the present study opens the door to the exploration of the causal effects highlighted in the analyses, which could have a great importance for the biodiversity of the different Melolonthidae beetle guilds.

In the context of neutron science, Bayesian inference methods have been recently implemented within the MANTID framework [Monserrat D et al. 2015 J. Phys. Conf. Ser. 663 012009 (2015)]. In this contribution, we highlight the advantages of this software package for robust data analysis and subsequent model selection. To this end, we use the celebrated Rosenbrock function to illustrate its merits and strengths relative to classical fitting algorithms. We also introduce the latest additions implemented in MANTID, with a view to increasing its user friendliness as well as stimulating wider use. These include simulated-annealing schemes to reduce the need for initial guesses, as well as new options for multidimensional fitting. © Published under licence by IOP Publishing Ltd.

8 pags.; 4 figs.; 3 tabs.; 7th IDMRCS: Relaxation in Complex Systems, © 2014 Elsevier B.V. All rights reserved. The thermal conductivity of CBrnCl4 -n,(n = 0,1,2) and 2-adamantanone (C10H14O) crystals which exhibit substitutional disorder has been measured for temperatures between 2 K and 150 K. Such temperatures comprise signatures of dynamical processes involving the site occupancy of the chlorine and bromine atoms for CBrnCl4 -n,(n = 0,1,2) and the oxygen atom for (C10H14O), as it has been revealed by both, calorimetry and spectroscopic techniques. The data analysis is carried out in terms of several phonon scattering channels contributing to a resistive relaxation rate which can be represented by two contributions due to propagating phonons whose mean-free path exceeds half the phonon wavelength as well as a term attributed to localized short wavelength modes. The implications of the present findings for studies pertaining to glassy dynamics are briefly discussed., This work is supported by the Spanish Ministry of Science and Innovation (grant no. FIS2011-24439), the Catalonia Government (grant no. 2009SGR-1251). The authors acknowledge the support from the National Academy of Science of Ukraine in the frame of the joint Ukrainian– Russian Project (agreement no. 10-2012) on the subject “Metastable states of simple condensed systems”. One of us A.I. K. thanks the Spanish Ministry of Education (grant SAB2011-0070) for an invited position at the Universitat Politècnica de Catalunya.

6 pags., 5 figs., We present a dynamic and thermodynamic study of the orientational glass former Freon 113 (1,1,2-trichloro-1,2,2-trifluoroethane, CCl2F-CClF2) in order to analyze its kinetic and thermodynamic fragilities. Freon 113 displays internal molecular degrees of freedom that promote a complex energy landscape. Experimental specific heat and its microscopic origin, the vibrational density of states from inelastic neutron scattering, together with the orientational dynamics obtained by means of dielectric spectroscopy have revealed the highest fragility value, both thermodynamic and kinetic, found for this orientational glass former. The excess in both Debye-reduced specific heat and density of states (boson peak) evidences the existence of glassy low-energy excitations. We demonstrate that early proposed correlations between the boson peak and the Debye specific heat value are elusive as revealed by the clear counterexample of the studied case., This work has been partially supported by the Spanish MINECO through Projects No. FIS2014-54734-P and FIS2014-54498-R and MAT2014-57866-REDT and “María de Maeztu” Program for Units of Excellence in R&D (MDM-2014-0377). We also acknowledge the Generalitat de Catalunya under Project No. 2014SGR-581 and the Autonomous Community of Madrid through program NANOFRONTMAG-CM (S2013/MIT-2850).

Pendulums have long been used to to determine the kinematics of non-inertial rotating systems. A proper study of this classical mechanical device under the action of a rotating reference frame can fully describe the behavior of such non-inertial systems. In such venue, we have placed a pendulum inside a rotating plane ride in an amusement park, and determined the parameters defining the rotation of the ride by solely analyzing the pendulum's motion. We present two different methodologies to determine the motion patterns of the ride as well as a computer-based reproduction of the trajectory of the pendulum throughout the ride.

Amusement parks are excellent laboratories of physics, not only to check physical laws, but also to investigate if those physical laws might also be applied to human behaviour. A group of Physics Engineering students from Universitat Politecnica de Catalunya has investigated if human behaviour, when driving bumper cars, can be modelled using tools borrowed from the analysis of molecular dynamics simulations, such as the radial and angular distribution functions. After acquiring several clips and obtaining the coordinates of the cars, those magnitudes are computed and analysed. Additionally, an analogous hard disks system is simulated to compare its distribution functions to those obtained from the cars' coordinates. Despite the clear difference between bumper cars and a hard disk-like particle system, the obtained distribution functions are very similar. This suggests that there is no important effect of the individuals in the collective behaviour of the system in terms of structure. The research, performed by the students, has been undertaken in the frame of a motivational project designed to approach the scientific method for university students named FISIDABO. This project offers both the logistical and technical support to undertake the experiments designed by students at the amusement park of Barcelona TIBIDABO and accompanies them all along the scientific process.

Fisidabo is an educational project aimed at promoting critical thinking among students. Under the framework of this project, and motivated by the ubiquitous qualitative analogy between spacetime warping by massive objects and the deformation of a rubber sheet to explain general relativity, a group of engineering physics students have undertaken a study of the movement of a small ball on a trampoline bent by the presence of a heavy mass in its centre. As the literature states, similarities between how masses move under warped spacetime and under a bent trampoline are only qualitative. Some observed analogy flaws are described which can be useful for teaching general relativity. Triggered by the failure of this analogy, a complete study of the movement of particles in a bent rubber sheet is developed. Several models to describe such trajectories and the resulting shape of the trampoline are proposed. Most importantly, a fitting routine to obtain the parameters needed for the description of the real trajectory is presented. The high accuracy between optimised and real trajectories recorded by a video camera implies that the model is able to explain the experimental behaviour.

It is hitherto thought that liquid water is composed of tetrahedrally coordinated molecules with an asymmetric interaction of the central molecule with neighboring molecules. Kuhne et al., Nat. Commun., 2013, 4, 1450 suggested that this asymmetry, energetic rather than geometric, is the cornerstone to reconcile the homogeneous and inhomogeneous viewpoints of liquid water. In order to investigate the geometric origin of that asymmetry, we have scrutinized Molecular Dynamics (MD) simulations of water through a careful analysis of the five-dimensional probability distribution function of Euler angles in which the relative positions and orientations of water molecules are obtained. We demonstrate that, beyond the ubiquitous tetrahedral structure with well-defined molecular dimers, there is a series of possible molecular orientations that define the structure. These orientations are generated by rotating the neighboring molecule around the O-H axis that is involved in the hydrogen bond scheme. Two of the possible orientations have a higher probability, giving rise to two kinds of dimers: one close to the lowest energy of a water dimer in vacuum with an almost perpendicular alignment of the dipole moment, and another one with a parallel orientation of the dipole moment which is less tightly bound. These two different dimers have an effect on the orientation of further water dipole moments up to a distance of approximate to 6 angstrom. Liquid water can therefore be described as a continuous mixture of two kinds of dimers where the hydrogen bonds have the same geometry but the interaction energies are different due to a different mutual orientation of the dipoles of the participating water molecules.

With the aim of finding a correlation between the crystallization kinetics and the molecular dynamics of a substance that would allow prediction of its crystallization time as a function of temperature for a given a relaxation time, we have studied stiripentol, an anticonvulsant drug. Stiripentol has been characterized in its supercooled liquid, amorphous (glass), and crystalline states by the concurrent use of broadband dielectric spectroscopy (BDS), differential scanning calorimetry, X-ray diffraction, and optical microscopy. BDS was employed to study both the dipolar molecular dynamics and the kinetics of crystallization from the melt. Three different molecular relaxation dynamics were identified: an a relaxation corresponding to the collective reorientation of the molecules and associated with the glass transition (Tg = 246.2 ± 0.5 K), a Johari Goldstein ß relaxation that can be associated with the single-molecule precursor of the a process, and a ¿ relaxation arising from intramolecular motions. Isothermal crystallization of Stiripentol was studied by means of BDS well above the glass transition (between 273 and 293 K), and it was observed under optical microscope at ambient conditions. Stiripentol did not exhibit any sign of polymorphism at ambient pressure, and it recrystallized from the melt into its stable crystalline form. The crystallization kinetics did not obey the Avrami law. Stiripentol displayed a very low nucleation rate, and drops of liquid stiripentol were observed to crystallize completely from a single nucleus before the appearance of new nuclei, so that the crystallite grew according to the morphology of the liquid domains, a fact that might explain the lack of validity of the Avrami law. Possible correlations between the crystallization kinetics and the molecular dynamics have been analyzed, finding that the crystallization time has a sublinear dependence on the cooperative relaxation time, as is the case in other substances reported in the scientific literature. This could suggest a general correlation of these parameters, at least at temperatures above Tg. The low nucleation rate is an interesting feature in the quest of possible mechanisms that allow enhancing the physical stability of amorphous drugs

Globular molecules of 1-chloroadamantane form a plastic phase in which the molecules rotate in a restrained way, but with their centers of mass forming a crystalline ordered lattice. Plastic phases can be regarded as test cases for the study of disordered phases since, contrary to what happens in the liquid phase, there is a lack of stochastic translational degrees of freedom. When the temperature is increased, a hump in the specific heat curve is observed indicating a change in the energetic footprint of the dynamics of the molecules. This change takes place without a change in the symmetry of the crystalline lattice, i.e. no first-order transition is observed between temperatures below and above the calorimetric hump. This implies that subtle changes in the dynamics of the disordered plastic phase concerning purely orientational degrees of freedom should appear at the thermodynamic anomaly. Accordingly, we describe, for the first time, the microscopic mechanisms behind a disorder–disorder transition through the analysis of neutron diffraction and QENS experiments. The results evince a change in the molecular rotational dynamics accompanied by a continuous change in density.

One of the more intriguing aspects of carbohydrate chemistry is that despite having very similar molecular structures, sugars have very different properties. For instance, there is a sensible difference in sweet taste between glucose and trehalose, even though trehalose is a disaccharide that comprised two glucose units, suggesting a different ability of these two carbohydrates to bind to sweet receptors. Here we have looked at the hydration of specific sites and at the three-dimensional configuration of water molecules around three carbohydrates (glucose, cellobiose, and trehalose), combining neutron diffraction data with computer modelling. Results indicate that identical chemical groups can have radically different hydration patterns depending on their location on a given molecule. These differences can be linked with the specific activity of glucose, cellobiose, and trehalose as a sweet substance, as building block of cellulose fiber, and as a bioprotective agent, respectively. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editors: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.

A series of molecular dynamics simulations have been conducted in order to study the specific ion effects of Li+, Na+, Cs+ and NH4+ cations on dodecyl sulfate (DS-) monolayers. Varying the counterion had no appreciable effect on the structure of the surfactant molecules within the different monolayers. However, the different counterions have a significant effect on the interfacial properties of the monolayer. In particular, we have investigated to what extent each of the counterions is dehydrated when interacting with the DS- headgroup, the specific interactions between the counterions and the headgroup and the salt bridging of the headgroups caused by each counterion. The NH4+ ions are found to directly compete with water molecules to form hydrogen bonds with the DS- headgroup and as a result the ammonium dodecyl sulfate monolayer is the least hydrated of any of those studied. The Cs+ ions are strongly bound to the headgroup and weakly hydrated, such that they would prefer to displace water in the DS- hydration shell to interact with the headgroups. In the case of the Li+ ions, they interact almost as strongly with the DS- headgroups as the Na+ ions, but are generally less hydrated than the Na+ ions and consequently the lithium dodecyl sulfate monolayers are less hydrated than the sodium dodecyl sulfate monolayers. Therefore, by changing the counterion, one can modify the interfacial properties of the surfactant monolayer, and thus affect their ability to encapsulate poorly water soluble drug molecules, which we discuss further in the manuscript.

Low-molecular weight cyclic alcohols as cycloheptanol (C7H14O, hereinafter referred to as cC7-ol) and cyclooctanol (C8H16O, cC8-ol) are prototypical materials displaying OD phases which, under fast cooling give rise to orientational glasses (OG). In addition to the ubiquitous α-relaxation of canonical glasses, several secondary relaxations appear for the mentioned systems (β and γ for cC8-ol and β for cC7-ol). The intramolecular character of these secondary relaxations for these materials as well as their mixed crystals was highlighted at temperatures close but above the glass transition. For lower temperatures the low values of dielectric strength makes difficult to account for the relaxation times obtained from the permittivity losses and, thus in this work we present a data analysis based on the Kramers–Kronig relations which connect the real and imaginary parts of dielectric permittivity and shows up a new method to make evident the existence of such secondary relaxations as well as to avoid phenomenological equations for determining the relaxation time.

Many theoretical models for the glassy dynamics have been proposed so far describing the changes in molecular dynamics along the extraordinary slowing down in the vitrification process of a disordered phase on cooling. Many of these theories share the concept of cooperative rearranging regions firstly proposed by Adam and Gibbs. Among them, the dynamical scaling model (DSM) is based on the random diffusion of free volume which creates random walking clusters formed by cooperatively rearranging entities. Within this framework a critical phenomenon relating a hidden phase transition at TC (below Tg) implies the divergence of the relaxation time (τ) or viscosity (η) τ, η ∝ (T − TC) − phi with a universal scaling exponent φ → 9. In this work we apply the DSM model to orientational glasses, obtained from the quenching of orientationally disordered phases (plastic crystals) via the application of the linearized derivative-based transformation of dielectric spectroscopy τ(T) data.

Cement paste is formed through a process called hydration by combining water with a cementitious material. Concrete, the worlds most versatile and most widely used material, can then be obtained when aggregates (sand, gravel, crushed stone) are added to the paste. The quality of hardened concrete is greatly influenced by the water confined in the cementitious materials and how it is transmitted through cracks and pores. Here we demonstrate that the water transport in cracks and capillary pores of hardened cement pastes can be approximately modeled by simple equations. Our findings highlight the significance of arresting the development of cracks in cementitious materials used in repository barriers. We also show that neutron scattering is an advantageous technique for understanding how water transmission is effected by gel pore structures. Defining measurable differences in gel pores may hold a key to prediction of the reduction of water transport through cement barriers.

Orientationally disordered (OD) mixed crystals formed between cyanoadamantane (CN-A) and chloroadamantane (Cl-A) have been thermodynamically characterized by means of thermal analysis and X-ray diffraction. The dynamics of these OD mixed crystals has been studied by means of broad band dielectric spectroscopy. Results evidence that dynamics of the α-relaxation process associated with the overall molecular tumbling slows down when molecules of CN-A are substituted by molecules of Cl-A.

The mechanism by which proteins are denatured by urea is still not well understood, especially on the atomic scale where these interactions occur in vivo. In this study, the structure of the peptide GPG has been investigated in aqueous urea solutions in order to understand the combination of roles that both urea and water play in protein unfolding. Using a combination of neutron diffraction enhanced by isotopic substitution and computer simulations, it was found, in opposition with previous simulations studies, that urea is preferred over water around polar and charged portions of the peptides. Further, it appears that while urea directly replaces water around the nitrogen groups on GPG that urea and water occupy different positions around the peptide bond carbonyl groups. This suggests that urea may in fact weaken the peptide bond, disrupting the peptide backbone, thus ultimately causing denaturation.

We use Bayesian inference methods to provide fresh insights into the sub-nanosecond dynamics of glycerol, a prototypical glass-forming liquid. To this end, quasielastic neutron scattering data as a function of temperature have been analyzed using a minimal set of underlying physical assumptions. On the basis of this analysis, we establish the unambiguous presence of three distinct dynamical processes in glycerol, namely, translational diffusion of the molecular centre of mass and two additional localized and temperature-independent modes. The neutron data also provide access to the characteristic length scales associated with these motions in a model-independent manner, from which we conclude that the faster (slower) localized motions probe longer (shorter) length scales. Careful Bayesian analysis of the entire scattering law favors a heterogeneous scenario for the microscopic dynamics of glycerol, where molecules undergo either the faster and longer or the slower and shorter localized motions.

To date there is a general consensus on the structure of the first coordination shells of liquid water, namely tetrahedral short range order of molecules. In contrast, little is known about the structure at longer distances and the influence of the tetrahedral molecular arrangement of the first shells on the order at these length scales. An expansion of the distance dependent excess entropy is used in this contribution to find out which molecular arrangements are important at each distance range. This was done by splitting the excess entropy into two parts: one connected to the relative position of two molecules and the other one related to their relative orientation. A transition between two previously unknown regimes in liquid water is identified at a distance of about similar to 6 angstrom: from a predominantly orientational order at shorter distances to a regime at larger distances of up to similar to 9 angstrom where the order is predominantly positional and molecules are distributed with the same tetrahedral symmetry as the very first molecules.

On the basis of the isostructural relationship between the low-temperature monoclinic ( C 2/ c , Z = 32) phases of the halogenomethane CBr 4− n Cl n ( n = 0, … , 4), a set of mixed crystals has been analysed by means of high-resolution X-ray powder diffraction. It is shown that the monoclinic structure of pure and mixed crystals does not depend of the particularities of the dipolar (or dipole induced) interactions of the pure compound, neither on the composition of the mixed crystal, but on the relative content of the halogen atoms which controls the size of the molecule or the average molecule for the case of mixed crystals.

The third-instar larva and pupa of the shining leaf chafer, Chrysophora chrysochlora (Latr.), from Cauca, Colombia, are described for the first time. Illustrations of diagnostic structures, modifications in the key to the larvae of the genera of Rutelini in the New World, and data on the biology and distribution of C. chrysochlora in Colombia are included.

Cocaine is an amphiphilic drug which has the ability to cross the blood–brain barrier (BBB). Here, a combination of neutron diffraction and computation has been used to investigate the atomic scale structure of cocaine in aqueous solutions. Both the observed conformation and hydration of cocaine appear to contribute to its ability to cross hydrophobic layers afforded by the BBB, as the average conformation yields a structure which might allow cocaine to shield its hydrophilic regions from a lipophilic environment. Specifically, the carbonyl oxygens and amine group on cocaine, on average, form ~5 bonds with the water molecules in the surrounding solvent, and the top 30% of water molecules within 4 Å of cocaine are localized in the cavity formed by an internal hydrogen bond within the cocaine molecule. This water mediated internal hydrogen bonding suggests a mechanism of interaction between cocaine and the BBB that negates the need for deprotonation prior to interaction with the lipophilic portions of this barrier. This finding also has important implications for understanding how neurologically active molecules are able to interact with both the blood stream and BBB and emphasizes the use of structural measurements in solution in order to understand important biological function.

The promotion of biodiversity conservation strategies must address the lack of information and the difficulty of identifying knowledge gaps that may facilitate our knowledge of different taxonomic groups. Dung beetles constitute one of those groups, despite having been proposed as an efficient bioindicator of environmental disturbance processes. In this work, we aimed to prepare a diagnosis on the state of knowledge of the subfamily Scarabaeinae, focusing on the cover sampling degree of this group in Colombia, with the purpose of identifying high-priority areas that will allow the completion of a national inventory. The work consisted of a bibliographical compilation using 12 referential databases and the examination of specimens deposited in 26 national collections. A total of 16 940 individuals were examined, finding registers for 232 species from 386 localities. The respective distribution cover maps were presented, and the cover at a national level was 10.62%. A historical analysis demonstrated a proliferation in the number of studies for the last three decades; nevertheless, a great proportion of unpublished works persists, resulting in only 64 sampled localities with published records. The localities with the greatest sampling efforts were RN La Planada, Lloro, AUN Los Estoraques, PNN Tinigua and Mariquita. Registries for all departments were available, and the best sampled ones were Cundinamarca, Antioquia, Valle del Cauca and Boyaca. The ecosystems with the greatest number of publications are the Andean pre mountain humid forest, followed by the Andean mountain humid forest and the Pacific humid forest. Other ecosystems with few studies included mangroves, desert zones, natural savannahs, palm swamps, paramos, flooding forests and agroforestry systems. The biogeographic region with the greatest number of localities was the Andean region, followed by Choco-Magdalenense and Amazonia. Our results showed that high levels of subsampling persist and that some zones lack registries, as in the case of some parks of the national system of protected areas. It is imperative that the sampling cover is extended at a national level, focusing all possible efforts on collecting in those subsampled regions that have high conservation importance, with the main goal of completing the listing of species and their distribution.