Poly[[(acetonitrile)­lithium(I)]-μ3-tetra­fluoridoborato]

The structure of the title compound, [Li(BF4)(CH3CN)]n, consists of a layered arrangement parallel to (100) in which the Li+ cations are coordinated by three F atoms from three tetra­fluoridoborate (BF4 −) anions and an N atom from an acetonitrile mol­ecule. The BF4 − anion is coordinated to three different Li+ cations though three F atoms. The structure can be described as being built from vertex-shared BF4 and LiF3(NCCH3) tetra­hedra. These tetra­hedra reside around a crystallographic inversion center and form 8-membered rings

Is the reputation of Eucalyptus plantations for using more water than Pinus plantations justified?

The effect of Eucalyptus plantations on water balance is thought to be more severe than for commercial alternatives such as Pinus species. Although this perception is firmly entrenched, even in the scientific community, only four direct comparisons of the effect on the water balance of a Eucalyptus species and a commercial alternative have been published. One of these, from South Africa, showed that Eucalyptus grandis caused a larger and more rapid reduction in streamflow than Pinus patula. The other three, one in South Australia and two in Chile, did not find any significant difference between the annual evapotranspiration of E. globulus and P. radiata after canopy closure. While direct comparisons are few, there are at least 57 published estimates of annual evapotranspiration of either a Eucalyptus or Pinus species. This paper presents a meta-analysis of these published data. Zhang et al. (2004) fitted a relationship between the crop factor and the climate wetness index to published data from catchment studies and proposed this approach for comparing land uses. We fitted the same model to the published data for Eucalyptus and Pinus and found that the single parameter of this model did not differ significantly between the two genera (p=0.48). This implies that for a given climate wetness index the two genera have similar annual water use. The residuals compared to this model were significantly correlated with soil depth for Eucalyptus, but this was not the case for Pinus. For Eucalyptus the model overestimates the crop factor on deep soils and underestimates the crop factor on shallow soils.</p

Is the reputation of Eucalyptus plantations for using more water than Pinus plantations justified?

The effect of Eucalyptus plantations on water balance is thought to be more severe than for commercial alternatives such as Pinus species. Although this perception is firmly entrenched, even in the scientific community, only four direct comparisons of the effect on the water balance of a Eucalyptus species and a commercial alternative have been published. One of these, from South Africa, showed that Eucalyptus grandis caused a larger and more rapid reduction in streamflow than Pinus patula. The other three, one in South Australia and two in Chile, did not find any significant difference between the annual evapotranspiration of E. globulus and P. radiata after canopy closure. While direct comparisons are few, there are at least 57 published estimates of annual evapotranspiration of either the Eucalyptus or Pinus species. This paper presents a meta-analysis of these published data. Zhang et al. (2004) fitted a relationship between the vegetation evaporation efficiency and the climate wetness index to published data from catchment studies and proposed this approach for comparing land uses. We fitted this model to the published data for Eucalyptus and Pinus and found that the single parameter of this model did not differ significantly between the two genera (p = 0.48). This was also the case for all parameters of an exponential relationship between evapotranspiration and rainfall (p = 0.589) and a linear relationship between the vegetation evaporation index and rainfall (p = 0.155). These results provide strong evidence that, for a given climate wetness index, the two genera have similar annual water use. The residuals compared to the model of Zhang et al. (2004) were significantly correlated with soil depth for Eucalyptus, but this was not the case for Pinus. For Eucalyptus, the model overestimates the vegetation evaporation efficiency on deep soils and underestimates the vegetation evaporation efficiency on shallow soils

Manufacture and use of ornaments made on carnivore teeth from archaeological sites of Low Paraná Wetland

En este trabajo se analizan una serie de piezas dentarias de carnívoros discutiendo su utilización como objetos ornamentales por las poblaciones humanas que ocuparon el sector meridional del humedal del Paraná inferior durante el Holoceno tardío. La identificación taxonómica de los distintos elementos dentarios se efectuó mediante estudios morfométricos, siendo de particular interés señalar el reconocimiento de especies que son poco frecuentes o que hasta ahora no estaban presentes en el registro arqueológico regional como Canis familiaris y Nasua nasua. A través del análisis microscópico, logramos identificar distintos rastros o huellas de transformación y utilización de los dientes, incluso en aquellos ejemplares que a ojo desnudo no presentaban modificaciones antrópicas. En función de los resultados obtenidos se discute la obtención y uso de estos objetos como objetos ornamentales y se realizan distintas consideraciones en cuanto a su potencial valor simbólico, señalando ciertas limitaciones interpretativas que existen sobre este tópico, así como las vías analíticas y conceptos desarrollados por otros autores para abordar problemáticas similares a las aquí estudiadas.This paper analyses Carnivore dental items, discussing their use as ornaments by human societies that inhabited the southern sector of Low Paraná wetland during the Late Holocene. Taxonomic identification of dental items was made trough morphometric analysis. It is very interesting to show the presence of taxa not available in the area as Canis familiaris and Nasua nasua. Through microscopic analysis, we identified use and manufacture process, also in those items which do not show anthropic modification at the naked eye. On the basis of these results, we discuss the bone raw material acquisition and their use as ornaments, arguing their symbolic value but pointing the analytical restrictions on this subject, as well as the methodological and theoretical lines developed by other authors to deal with similar topics.Fil: Acosta, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; ArgentinaFil: Buc, Natacha. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; ArgentinaFil: Ramirez, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Biológica de Usos Múltiples (Sede Corrientes); ArgentinaFil: Prevosti, Francisco Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Biológica de Usos Múltiples (Sede Corrientes); ArgentinaFil: Loponte, Daniel Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentin

High-frequency photothermal processing of commercial polymers under femtosecond laser irradiation for waveguide writing

The processing of three commonly used commercial polymer films (poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET) and polypropylene (PP)) with different thermal properties under femtosecond (450 fs) irradiations at high frequency (1 kHz-1 MHz) multi-pulse (N=10-18000) laser at λ=515 (1.34 J/cm2, radius 9 μm) is analysed in order to have knowledge of which material and laser conditions are more suitable to write waveguides. Thermal and ablative effects are observed after laser irradiations. Heat accumulation effects of successive pulses impinging are simulated through a photothermal model in order to explain the results of irradiating these materials. Thermal analyses (Modulated Differential Scanning Calorimetry (MDSC) and Thermogravimetry (TG)) are performed and used to explain the different behaviour of each polymer. Three different regimes (non-thermal, thermal and saturation) are identified and explained from the model and experimental results. A connection between ablation depth and simulated reached temperature is established. A study of which number of pulses/spot area and frequency are appropriate for a better shape and ablation depth for writing waveguides on these polymers is performed.The work was supported by “Generalitat Valenciana” (IDIFEDER/2021/014 cofunded by FEDER program, project PROMETEO/2021/006, and INVEST/2022/419 financed by Next Generation EU), “Ministerio de Ciencia e Innovación” of Spain (projects PID2021-123124OB-I00; PID2019-106601RB-I00) and UATALENTO18-10 by “Universidad de Alicante”

Efficient and stable holographic gratings stored in an environmentally friendly photopolymer

Holographic gratings stored in low-toxicity photopolymer, Biophotopol, have been analyzed to achieve stable and efficient holograms. A curing process allows the hologram stabilization, but at the same time, it could produce a diffraction efficiency (DE) reduction. Here, a detailed low-cost LED curing protocol is shown to stabilize over time 1205 l/mm transmission holograms, and at the same time, a 33% DE increment (with respect non-curing holograms) have been demonstrated. Finally, to obtain a better understanding of DE change, a theoretical fit of our experimental result, based on Kogelnik’s coupled wave theory was carried out and discussed.Ministerio de Ciencia, Innovación y Universidades, Spain, under projects FIS2017-82919-R (MINECO/AE/FEDER, UE) and FIS2015-66570-P (MINECO/FEDER); Generalitat Valenciana, Spain, under project CDEIGENT/2018/024 and GRE17-06

Efficient and stable holographic gratings stored in an environmentally friendly photopolymer

Holographic gratings stored in one of the greenest photopolymers, called Biophotopol and patented by Holography and Optical Processing group at the University of Alicante, have been analyzed to achieve stable over time and efficient holograms. A curing process usually produces a diffraction efficiency (DE) decrement. However, when a curing process is not performed, the holographic gratings are not stable and DE will decrease over time due to the diffusion of molecular components inside the photopolymer. In this work, a DE increment has been demonstrated after a curing stage (performed with an incoherent and lowcost LED lamp). A detailed curing protocol to stabilize the holograms while maintaining high DE, has been carried out in unslanted transmission gratings of 1205 l/mm. The holographic transmission reflection setup allows the possibility to evaluate the transmitted and diffracted intensity beam relation, in real time, by using a He-Ne laser (633 nm), while the gratings were recording with an Argon laser (488 nm). It has been demonstrated more than a 30% DE increment after a curing process when a maximum DE in the recording stage had not been still achieved. However, in the singular case that a maximum DE in the recording stage has been already obtained, a curing stage process could produce overmodulation effects, and therefore, a DE decrement. In conclusion, a maximum DE is obtained in curing and stable hologram gratings (recording them with proper radiant exposures) over an environmentally compatible photopolymer.This work was supported by the “Ministerio de Ciencia, Innovación y Universidades” (Spain) under projects FIS2017-82919-R (MINECO/AE/FEDER, UE) and FIS2015-66570-P (MINECO/FEDER) ang by the University of Alicante under project GRE17-06. M.M-V. acknowledge the financial support by the "Generalitat Valenciana” (Spain) under grant CDEIGENT/2018/024

La emigración internacional, las remesas y el desarrollo económico en México

La migración es un fenómeno que ocurre desde el momento en que el hombre busca nuevas alternativas para mejorar su bienestar social, su aspecto benéfico radica en el flujo de remesas captadas en las regiones expulsoras de mano de obra, las cuales se encuentran concentradas principalmente en las zonas rurales. La tendencia en el uso de las remesas está encaminada hacia la satisfacción de las necesidades básicas, así como a la adquisición de bienes de consumo y a la compra y mejora de la vivienda de las familias de los migrantes. Existen países que tienen flujos migratorios masivos, motivo por el cual reciben flujos importantes de remesas para su contabilidad nacional y en este trabajo se analizan desde la perspectiva de países expulsores y de destino de la mano de obra migrante. Por facilidad de análisis de esta obra los países se agrupan en cinco regiones, a saber; África, Asia, Europa, Latinoamérica y Oceanía. Para nuestro país la captación de divisas por concepto de las exportaciones petroleras es la más importante, pero a partir del año 2000, éstas constantemente se ven amenazadas por los flujos monetarios que ingresan al país por concepto de remesas y que desde el año 2003 se colocaron como la segunda fuente más importante de divisas para México. La necesidad de conocer los efectos de las remesas sobre la conomía mexicana se debe a que representan un flujo monetario que en más del 80% es destinado al autoconsumo y el resto a la inversión o ahorro, lo que sin duda genera burbujas inflacionarias para las regiones que mayoritariamente reciben tales ingresos como en el caso de los estados de Jalisco, Michoacán, Zacatecas, o el mismo Estado de México