Synthesis, crystal structures, Hirshfeld surface analysis and physico-chemical characterization of two new ZnII and CdII halidometallates

Two new organic–inorganic hybrid materials, based on 1, 3-CycloHexaneBis-(Methyl Amine), abbreviated CHBMA, namely (H2CHBMA)ZnCl4·2H2O (CP1) and (H2CHBMA)CdI4·2H2O (CP2), have been synthesized under mild conditions in acidic media and characterized by single-crystal X-ray diffraction, spectroscopic techniques (13C NMR, FTIR, RAMAN) and thermal analysis. The crystal structures of the two compounds were solved by single-crystal X-ray diffraction methods. Both compounds show a 3-dimensional supramolecular structure directed by various interactions between tetrahalidometallate anions (ZnCl42-, CdI42-), water molecule and organic cations (H2CHBMA)2+. For both compounds, the cyclohexane ring of the template cation is in a chair conformation with the methylammonium substituent in the equatorial positions and the two terminal ammonium groups in a cis conformation but with two different orientations (upward for CP1 and downward for CP2) which influences the supramolecular architecture of the two structures. Hirshfeld surface analysis and the associated two-dimensional finger print plots were used to explore and quantify the intermolecular interactions in the crystals

Patrones de variabilidad de las microalgas epibentónicas en la costa este tunecina

Epiphytic microalgae were monitored on various substrates of seagrass and macroalgae and in the water column for one year (from March 2013 to March 2014) in Oued Lafrann along the eastern coast of Chebba (Tunisia) with a focus on the distribution patterns of the epibenthic toxic dinoflagellates Ostreopsis cf. ovata, Prorocentrum lima and Coolia monotis. Microalgae assemblages were dominated by diatoms and dinoflagellates both in the water column and on vegetation. High concentrations of epiphytic toxic and potentially toxic dinoflagellates were preferentially hosted by Posidonia leaves, mainly in the apical and middle regions of the leaves, and P. lima was the dominant species. A significant positive correlation was found between P. lima concentrations on Posidonia and in the water column, suggesting that macrophytes should be sampled in the framework of harmful algal species monitoring. Ostreopsis cf. ovata, exhibited low concentrations and was mainly present on the inner surface of the Posidonia leaf, whereas P. lima was mainly present on the outer surface of the leaf, suggesting a likely space competition.Las microalgas epifitas fueron monitorizadas en varios sustratos de praderas marinas, macroalgas y en la columna de agua durante un año (de marzo 2013 hasta marzo 2014) en Oued Lafrann, en la costa este de Chebba (Túnez), con especial atención a la distribución de dinoflagelados tóxicos epibénicos, como Ostreopsis cf. ovata, Prorocentrum lima y Coolia monotis. Las comunidades de microalgas estaban dominadas por diatomeas y dinoflagelados, tanto en la columna de agua como en la vegetación. Se encontraron elevadas concentraciones de dinoflagelados epífitos tóxicos preferentemente en las hojas de Posidonia, principalmente en las regiones apicales y media y Prorocentrum lima fue la especie epífita dominante. Se observó una correlación positiva significativa entre las concentraciones de P. lima en Posidonia y en la columna de agua, lo que sugiere el muestreo de esta macrófita como parte de la monitorización de especies nocivas. Las células de Ostreopsis cf. ovata mostraron concentraciones bajas y se encontraron principalmente en la superficie interior de la hoja de Posidonia contrariamente a la distribución de P. lima presente principalmente en la superficie exterior de la lámina. Este hecho probablemente sugiere una competencia espacial entre los dos microalgas tóxicas

Single-crystal-to-single-crystal transformation and catalytic properties of new hybrid perhalidometallates

Two new organic–inorganic salts of perhalidometallates with protonated organic amine cations have been synthesized and characterized by X-ray diffraction and thermal analysis. (CHBMAH2) ZnBr4·3/2H2O 1 and (CHBMAH2 )ZnCl4 4 [(CHBMAH2 )2+: 1, 3-cyclohexanebis(methylammonium)] were obtained in single-crystal form. The crystal packing in all of the obtained compounds is governed by the formation of various non-covalent intermolecular forces between tetrahalidometallate anions and organic cations, assisted by water molecules in the hydrates. Hirshfeld surface analysis denotes that the most important contributions to the crystal packing are X···H/H···X (X: Cl, Br, I) and H···H interactions. Interestingly, the compound 1, 3-cyclohexanebis(methylammonium)tetrachlorido-zincate (II) dihydrate, (CHBMAH2 )ZnCl4·2H2O 2, undergoes thermally-triggered single-crystal-to-single-crystal (SCSC) transformation upon dehydration to produce a supramolecular solid compound, 1, 3-cyclohexanebis(methylammonium) tetrachloridozincate (II), (CHBMAH2 )ZnCl4 4. The SCSC transformation causes changes in the lattice parameters and a structural rearrangement. Furthermore, the catalytic properties of (CHBMAH2 )ZnCl4·2H2O 2 and (CHBMAH2 )CdI4·2H2O 3 have been explored in the acetalization process using various uncommon alcohols, beyond methanol or ethanol, for the first time in the literature, with outstanding results, and opening the door to the formation of alternative acetals. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Research of the origin of a particular Tunisian group using a physical marker and Alu insertion polymorphisms

The aim of this study was to show how, in some particular circumstances, a physical marker can be used along with molecular markers in the research of an ancient people movement. A set of five Alu insertions was analysed in 42 subjects from a particular Tunisian group (El Hamma) that has, unlike most of the Tunisian population, a very dark skin, similar to that of sub-Saharans, and in 114 Tunisian subjects (Gabes sample) from the same governorate, but outside the group. Our results showed that the El Hamma group is genetically midway between sub-Saharan populations and North Africans, whereas the Gabes sample is clustered among North Africans. In addition, The A25 Alu insertion, considered characteristic to sub-Saharan Africans, was present in the El Hamma group at a relatively high frequency. This frequency was similar to that found in sub-Saharans from Nigeria, but significantly different from those found in the Gabes sample and in other North African populations. Our molecular results, consistent with the skin color status, suggest a sub-Saharan origin of this particular Tunisian group

A single-item continuous review inventory problem with space restriction

With today's high cost of land acquisition observed in most countries, management can no longer afford large storage facilities to house their products. For this reason, one of the main concerns of inventory managers is to ensure that enough storage space is available upon the delivery of a product. They, therefore, have to determine the least cost ordering policy so as to meet demand and taking into account the space limitation. In this paper, we investigate the problem of a single item continuous review inventory problem in the presence of a space restriction when the demand is stochastic. Through a sensitivity analysis study, it is found that ordering cost, storage capacity, average demand per unit time, and holding cost rate are the most influential problem parameters on the expected inventory costs. It is also shown numerically that a simple solution based on economic order quantity is performing very well with an average and maximum cost penalty of 0.19% and 2.03%, respectively.(Q, R) continuous review model Ordering quantity Reorder point Space restriction