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An ichnological analysis of the Paleocene–Eocene Wilcox Formation at San José de la Laja and La Curva localities within the Burgos Basin in northeastern Mexico revealed seven ichnogenera: Chondrites , Diplocraterion , Ophiomorpha , Palaeophycus , Planolites , Sinusichnus and Skolithos . The trace fossils were grouped into different ichnoassemblages, including a detailed facies analysis. These results show their apparent association with the Skolithos and Cruziana Ichnofacies in the two studied localities. The integrative analysis of trace fossils and lithofacies made it possible to infer plausible depositional environments for registered periods of fair-weather conditions in both localities of the Burgos Basin, which represent ecosystems characterized by low diversity and abundance. In San José de La Laja, the environment varies from storm affected to tidal setting. In La Curva, lithofacies and ichnology are modulated by storm events in a transitional shoreface, coastal bar and intertidal setting within a deltaic plain. Both localities indicate a shelf impacted by deltaic processes and storm events. Living conditions for most endobenthic organisms were harsh. These results support a long-term regression of the coastal zone during the Paleogene–Neogene and suggest a palaeoenvironment similar to this in the south of Texas during the Paleogene.

El confinamiento y las restricciones de movilidad durante la pandemia de COVID-19 han dado lugar auna serie de dilemas sobre el uso y percepción del espacio público, donde sus propiedades relacionalesy contextuales pueden dar lugar a una diversidad de emociones. Con la aplicación de herramientas machinelearning y social network analysis, exploramos emociones sobre el espacio público basadas enatributos de imágenes fotográficas en la ciudad de Quito, Ecuador, tomadas entre abril y junio de 2020.Los resultados muestran emociones positivas y negativas asociadas a un mismo atributo del paisajeurbano, mientras que atributos que pueden considerarse opuestos (como “brillante” y “sucio”) podríantener mayor influencia en los sentimientos positivos sobre dicho espacio. Esta investigación abre unnuevo campo de estudio en la región sobre las emociones urbanas, y ofrece un mejor entendimiento delas percepciones de los ciudadanos sobre el espacio público durante la crisis de la pandemia.

Depositional episodes are readily identified along representative localities of the Lower Cretaceous Cupido platform in northeastern Mexico. The basal part of the Cupido Formation exhibits a progradational reef platform that, at the upper limit, is truncated by a sequence boundary defined by a breccia. This breccia marks the development of a peculiar sedimentary facies informally known as the Cupidito unit, a distinctive stratigraphical unit in northeastern Mexico that remained uninterpreted for decades. Through the analysis of facies, microfacies and stable isotope comparisons from representative localities (Potrero Chico, Potrero de García, La Huasteca, La Muralla and Puerto Mexico) and from other previously reported outcrops, this work describes six diagnostic features for Cupidito and an improved stratigraphic model is proposed. The depositional sequence suggests a broad flat-topped platform with a general low organic productivity and restricted conditions followed by recurrent inundations of lagoon waters. Before drowning, this carbonate platform remained under equilibrium conditions interrupted by short pulses of relative higher-temperatures (48.3 °C and 39.2 °C). Coral-rudist-stromatoporoid patch-reefs with inferred inter-tropical temperatures between 31.5 °C and 32.2 °C originated as a progradational response to the instauration of a new Sequence Boundary at the base of Cupidito.

La violencia contra las mujeres, en cualquier etapa de la vida, constituye una violación a sus derechos humanos y a sus libertades fundamentales, por lo que existe un amplio marco jurídico internacional que sustenta y protege contra la violencia relacionada con la salud reproductiva. El concepto de violencia obstétrica es relativamente nuevo y aún poco conceptualizado, relacionado de manera casi exclusiva al periodo del parto. La violencia obstétrica se entiende como cualquier forma de violencia por la que pase la mujer durante el embarazo y el proceso de parto. Comprende todo daño físico, sexual, psicológico, emocional, laboral o económico para las mujeres y la coacción o la privación arbitraria de su libertad. La institucionalización, la medicación excesiva, la falta de información relacionada a los procedimientos y el paternalismo médico que pueden ocurrir antes, durante y después del parto, han conducido al sometimiento de la mujer gestante a un abuso cotidiano por parte del personal de salud, convirtiéndose en un problema de salud pública y de derechos humanos, que se define como violencia obstétrica. En este documento se presenta una revisión del tema. LUXMÉDICA, AÑO 14, NÚMERO 41, MAYO-AGOSTO 2019, PP 43-58.

The present paper address the occurrence of Venericardia shell concentrations distributed over hundreds of meters along terrigenous horizons as a typical sedimentary facies of the Wilcox Formation in the Burgos Basin. These extensive deposits overlie Paleogene sandstones so common around the municipality of China, Nuevo Leon, that they are almost overlooked. This report documents for the first time the ichnological assemblage and shell accumulations of the Paleogene in the Burgos Basin. Ophiomorpha cf. nodosa and Ophiomorpha isp. from Skolithos ichnofacies are the main identified trace fossils; the probable paleoenvironment is a near-shore shallow sea under high-energy conditions related to coastal bars. The analyzed taphonomic features suggest that Venericardia shell concentrated or accumulated as bioevents resulting from intermitent tempestites in the proximal zone. These accumulations are composed of the species Venericardia (Venicor) zapatai organized as regular and linear shell arrangements contained within a frail sedimentary matrix from which they are easily-extracted.

A rich geobiological record of Cretaceous biotic and abiotic interactions around the proto-Gulf of Mexico has been preserved in the massive Cupido carbonate platform, i.e., in a sedimentary sequence that represents a depositional period of approximately 15 Myr. This work documents lateral facies variation on a dip slope reef from a new outcrop in the upper part of the Cupido Formation in the state of Nuevo Leon, Mexico. The measured transect is correlated with a stratigraphic column logged in a nearby section. The preserved fossil biota represents marginal reef facies dominated by abundant rudist shells such as Douvillelia skeltoni, Toucasia sp., Offneria sp., and Amphitrocoelus sp. associated with relatively large colonial corals (with diameters up to 25 cm) like Stelidioseris sp. and to a lesser extent, with stromatoporoids. Benthic foraminifers (miliolids and textularids) with associated dasycladalean algae such as Salpingorella sp. and Terquemella spp. dominate the microfossiliferous content in wackestones to packstones. This facies is overlain by a thin (15-30 cm) stromatolite horizon at the upper end of the measured section. This locality represents a new paleobiological and taphonomic window into one of the most extensive carbonate platform system developed along the margin of the Gulf of Mexico during the Cretaceous.

The demand for multifunctional requirements in aerospace, military, automobile, sports, and energy applications has encouraged the investigation of new composite materials. This study focuses on the development of multiwall carbon nanotube (MWCNT) filled polypropylene composites and carbon nanofiber composite mats. The developed systems were then used to prepare interlayered composites that exhibited improved electrical conductivity and electromagnetic interference (EMI) shielding efficiency. MWCNT-carbon nanofiber composite mats were developed by centrifugally spinning mixtures of MWCNT suspended in aqueous poly(vinyl alcohol) solutions. The developed nanofibers were then dehydrated under sulfuric acid vapors and then heat treated. Interlayered samples were fabricated using a nanoreinforced polypropylene composite as a matrix and then filled with carbon fiber composite mats. The in-plane and through-plane electrical conductivity of an eight-layered flexible carbon composite (0.65 mm thick) were shown to be 6.1 and 3.0 &times, 10&minus, 2 S&middot, cm&minus, 1, respectively. The EMI shielding effectiveness at 900 MHz increased from 17 dB for the one-layered composite to 52 dB for the eight-layered composite. It was found that the reflection of the electromagnetic waves was the dominating mechanism for EMI shielding in the developed materials. This study opens up new opportunities for the fabrication of novel lightweight materials that are to be used in communication systems.

The Jenchen's comment appears to assume that Venericardia and Ophiomorpha were the main objectives in our work and that we used random criteria to assign genera. However our paper addressed the presence of previously reported V. and Oph. from new localities rather than a taxonomic determination. Our descriptions of shells are based on the separate evaluation of observed macroscopic and microscopic features for taphonomic rather than taxonomic purposes. Based on this erroneous assumption, Jenchen disproves our methodology and data processing. Since Jenchen statements (ten remarks) are reiterative and redundant, we have simplified them and focus on the four main points: geological setting (three remarks), presentation of studied section (one remark), Ophiomorpha isp. (two remarks), and Venericardia (Venericor) zapatai (three remarks). In the following lines we'll argue why most of these comments lack robust scientific support and are rather suggestions on how our results should be worked, interpreted and presented. We expect to answer every remark. Due to the redundancy of his 3rd and 4th points, we simplified our clarifications in the same order. Since there seems to be a mistaken assumption in some of the commentaries embodied in the 2nd and 3rd sections of Jenchen's comment, the 5th section turns out to be invalid. We conclude answering his remarks concerning our treatment of data from sections 6th and 7th, and include some recommendations as well.

NO TIENE RESUMEN

Novel palladium complexes with BPPFA (N,N-dimethyl-1-[2,1‘-bis(diphenylphosphino)ferrocenyl]ethylamine) and the newly prepared ligand 1,1‘-bis(diphenylphosphino)-2-methylferrocene (BPPFMe, 1) have ...

In this paper a consensus problem is considered for leader-following of multiple wheeled mobile robots. Laplacian matrix is introduced to characterize the communication topology. Since there are parameter uncertainties for each mechanical system, adaptive control method is applied for controller design of the dynamical systems. Distributed adaptive state feedback control laws are presented with the aid of the agent's neighboring information. Simulation results are presented to validate the proposed control laws.

This paper considers distributed output tracking control of a leader. If the state of each system is measurable, distributed state feedback controllers are proposed such that the output of each system asymptotically converges to the output of the leader with the aid of the internal model principle. If the state of each system is not measurable, distributed output feedback controllers are proposed with the aid of state estimation such that the output of each system asymptotically converges to the output of the leader. Simulation study validates the proposed results.

New complexes of palladium(II), silver(I), copper(I) and ruthenium(II) containing the ligands 2-(pyrazol-1-yl)pyridine (pzpy), 2-(pyrazol-1-yl)pyrimidine (pzpm), 2-(3,5-dimethylpyrazol-1-yl)pyrimidine (pz*pm) and 4,6-bis(pyrazol-1-yl)pyrimidine (bpzpm) have been prepared and characterised. Only the isomer with the least steric hindrance was found for the derivatives PdClR(N–N′), R = Me or COMe, N–N′ = pzpy or pzpm, while the two possible isomers were found for similar derivatives with pz*pm. In the reaction of [RuCl2(cod)]n with pzpy, pzpm and bpzpm, the isomer trans-RuCl2(cod)(N–N′) was always formed. Three different isomers were consecutively formed after the reaction of RuCl2(PPh3)3 with bpzpm, with the thermodynamically stable isomer being cis,trans-RuCl2(PPh3)2(bpzpm). A fluxional process involving interchange of the H4/H6 pyrimidine protons, which implies M–N(pm) bond rupture, was found in the silver, copper and some palladium derivatives. Such an interchange was not observed in the ruthenium complexes. The trans influence of the group situated trans to the pyrimidine ring was found to be extremely important for Pd–N bond rupture. The isomer interconversion for the derivatives PdClR(pz*pm), R = Me or COMe, was studied by variable temperature 1H NMR studies. The process is of higher energy than the H4/H6 interchange and is facilitated by the presence of the acyl group.

A series of monohydrides of RuII of formula RuH(TpR)(cod) 1–3 have been synthesized from the reaction of [RuH(NH2NMe2)3(cod)]BPh4 with the corresponding TpR ligand {hydrotris(7-methylindazol-2-yl)borate, TpBo,7Me, 1; hydrotris[3-(2-thienyl)pyrazol-1-yl]borate, TpTn, 2; tris[3-(2,4-dimethoxyphenyl)pyrazol-1-yl]hydroborate, Tp(2,4(OMe)2Ph), 3}. In these compounds the Tp ligand is κ3N,N′,BH coordinated with a B–H ⋯ Ru agostic interaction. Reactions of 1 and 2 with two-electron donor ligands, L = PMe3, PMe2Ph and CN-t-Bu, led to the formation of complexes of formula RuH(TpR)(L)(cod) (TpR = TpBo,7Me, L = PMe34, PMe2Ph 5 or CN-t-Bu 6; TpR = TpTn, L = PMe37, PMe2Ph 8 or CN-t-Bu, 9). In this new series the incoming ligands replace one of the coordinated pyrazole rings instead of the stated B–H ⋯ Ru interaction which remains and consequently the TpR ligands are κ2N,BH coordinated. The molecular structure of 7 was determined by an X-ray diffraction study. The ruthenium atom has a distorted octahedral environment with the ligand TpTn coordinated through only one pyrazole ring and an agostic B–H group. The two hydrides are in a mutually trans disposition with an angle of 166°. The Ru ⋯ H distance is 2.07(5) and Ru–Hterminal 1.33(5) A. The molecular structure of the model complex [RuH(κ2-N,BH-Tp)(PH3)(H2CCH2)2] has been optimised with the aid of ab initio calculations in order to compare the structural parameters with those of the experimentally determined structure.

Two α-R substituted bis(3,5-dimethylpyrazol-1-yl)methane ligands (R=Ph, bpz*mPh and 2-py, bpz*mpy) have been used to synthesise new palladium(II) compounds with the general formulae PdXX′(bpz*mR) (R=Ph, X=X′=Cl; 1a , X=X′=Me; 2a , X=Cl, X′=Me; 3a , X=X′=C 6 F 5 ; 4a or R=2-py, X=X′=Cl; 1b , X=Cl, X′=Me; 3b , X=X′=C 6 F 5 , 4b ), [Pd(η 3 -2-CH 3 C 3 H 4 )(bpz*mR)]X (X=PF 6 − , R=Ph, 5a ; X =CF 3 SO 3 − , 2-py, 5b ) and [Pd(bpz*mR) 2 ](BF 4 ) 2 (R=Ph, 6a ; 2-py, 6b ). In all the complexes the bpz*mR ligands adopt a rigid conformation with the R group in an axial position and, as a consequence, no boat-to-boat interconversion is observed. In 1b and 3b – 5b the pyridine group is uncoordinated. Complex 5b is present as a single isomer, while 5a exists as two isomers that are in equilibrium and differ in the orientation of the allyl group with respect to the NN ligand. For complex 6b the four possible anti isomers are observed in solution. The molecular structures of the major isomer of 5a and one of the isomers of 6b have been determined by X-ray structure analysis. In both structures the bpz*mR ligands are coordinated as bidentate. For 5a the ligand backbone confirms the stated rigidity. For 6b a pyridine–pyrazole coordination of the two bpz*mpy ligands is observed. The fluxional behaviour implying interconversion of the two pyrazole rings in 3b , of the two isomers in 5a and the rotation of the C 6 F 5 groups in 4a and 4b has also been studied.

The ligands 4,6-bis(pyrazol-1-yl)pyrimidine (bpzpm) and 4,6-bis(4-methylpyrazol-1-yl)pyrimidine (Me−bpzpm) were synthesized and their reactions with some palladium derivatives explored. Mononuclear or dinuclear neutral or cationic complexes were obtained by reaction of the ligands with 1 or 2 equiv of Pd(C6XF4)2(cod) (cod = 1,5-cyclooctadiene; X = F, H) or the palladium fragment [Pd(η3-2-Me-C3H4)(S)2]+ (S = acetone). The reaction of the dinuclear derivatives with 1 equiv of the respective free ligand immediately led to the regeneration of the mononuclear complexes. Except in the case of the synthesis of [{Pd(C6HF4)2}{Pd(C6F5)2}(bpzpm)], where two similar metallic groups are present, all attempts to obtain dinuclear asymmetric complexes with two different palladium fragments failed. Instead, the dinuclear symmetric complexes were formed. This result could be considered as an example of molecular recognition with the ligand acting as a ditopic receptor. This behavior is comparable to chemical symbiosis but ...

The ligands 2,4,6-tris(4-methylpyrazol-1-yl)-1,3,5-triazine (Me-TPzT), 2,4,6-tris(4-bromopyrazol-1-yl)-1,3,5-triazine (Br-TPzT), and 2-methoxy-4,6-bis(4-methylpyrazol-1-yl)-1,3,5-triazine (Me-BPzTOMe) have been synthesized and their reactions with some palladium derivatives explored. The palladium fragment [Pd(η3-2-Me-C3H4)(S)2]+, S = acetone, reacts in acetone with Me-TPzT or Br-TPzT in a 3:1 molar ratio to generate new complexes in which two allylpalladium fragments are present and the TPzT ligands have been partially hydrolyzed: [{Pd(η3-C4H7)}2(X-BPzTO)]A, X-BPzTO = 4,6-bis[4-methyl(or bromo)pyrazol-1-yl]-1,3,5-triazin-2-olate (X = Me, A = BF4, 1; A = PF6, 2; A = CF3SO3, 3; A = p-MeC6H4SO3, 4; X = Br, A = CF3SO3, 5). When the ligand Me-BPzTOMe is made to react with only 1 equiv of the palladium solvate, compound 6, [Pd(η3-2-Me-C3H4)(Me-BPzTOMe)]CF3SO3, is isolated. Reaction of 6 with another 1 equiv of the palladium derivative leads to 3. The intermediate 7, [{Pd(η3-2-Me-C3H4)}2(Me-BPzTOMe)]CF3SO3, ha...

The (aminoferrocenyl)phosphine ligand 1-diphenylphosphino-2,1‘-(1-dimethylaminopropanediyl)ferrocene, 1, was used to synthesize new palladium(0) and -(II) complexes. The reaction of Pd2(dba)3·CHCl3...

Se reportan datos sobre el ciclo de vida, número de repastos sanguíneos para mudar de estadio ninfal, mortalidad y el porcentaje de hembras de híbridos de M. phyllosomus x M. mazzottii en comparación con cohortes “puras” de M. phyllosomus (Burmeister) y M. mazzottii (Usinger). El ciclo de vida fue significativamente (P0,05) entre cohortes en el número de repastos sanguíneos para mudar de estadio ninfal. El porcentaje de mortalidad (41.8%) de la cohorte parental de M. phyllosomus fue significativamente ( P0,05) entre las cuatro cohortes bajo estudio. Data is reported about life cycle, number of blood meal to molt to next instar, mortality and percentage of females on hybrids from crosses of M. phyllosomus x M. mazzottii compared to “pure” cohorts of M. phyllosomus (Burmeister) and M. mazzottii (Usinger). Recorded life cycle was significantly ( P0,05) differences were recorded in the number of blood meals to molt to next instar when the four studied cohorts were compared. Mortality percentage (41.8%) on the parental cohort of M. phyllosomus was significantly (P0,05) when the four studied cohorts were compared.

New examples of the fluxional behavior of (η3-allyl)palla-dium complexes are described. Variable-temperature experiments and line-shape analysis of two (η3-allyl)palladium complexes containing 2-(1H-pyrazol-1-yl)azine ligands were performed in order to determine the activation free energies, enthalpies and entropies of the process. A dissociative mechanism pointing to a selective Pd-N cleavage is proposed on the basis of these results and NOE experiments above and below the coalescence temperature.

Fuente TESIUNAM

The ligands 4,6-bis(pyrazol-1-yl)pyrimidine (bpzpm), 4,6-bis(3,5- dimethylpyrazol-1-yl)pyrimidine (bpz*pm), 4,6-bis-(4-methylpyrazol-1-yl) pyrimidine (Mebpzpm), and 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine (ppdMe) were synthesized and were made to react with Cu(I) centers in the presence of different counteranions. Different [2 x 2] metallic grids were obtained. With ligands bpzpm, bpz*pm, and Mebpzpm, a new type of grid was obtained where the facing ligands were divergent and two counteranions (BF4 - or PF6 -) were hosted in the resulting cavities and exhibit C-H⋯F and anion⋯π interactions in the solid state. The presence of methyl groups on the pyrazolyl rings induced several distortions in the structure. In complexes with the ligand ppdMe, there were found two groups of parallel ligands in the grid, and the cavities generated were smaller. The counteranions were situated outside the grid, and the facing ligands exhibited aromatic π-π stacking interactions. Anion-π interactions involving the pyridazine ring were found. The behavior in solution of the new derivatives with a special emphasis on the cation-anion interactions was studied by UV-vis and NMR spectroscopy. Diffusion NMR experiments performed for some complexes allowed us to conclude that weak cation-anion interactions exist in solution, with the counteranions undergoing fast exchange on the diffusion time scale between the free and ion-paired states. © 2008 American Chemical Society.

The ligands 2,4,6-tris(4-methylpyrazol-1-yl)-1,3,5-triazine (Me-TPzT), 2,4,6-tris(4-bromopyrazol-1-yl)-1,3,5-triazine (Br-TPzT), and 2-methoxy-4,6-bis(4-methylpyrazol-1-yl)-1,3,5-triazine (Me-BPzTOMe) have been synthesized and their reactions with some palladium derivatives explored. The palladium fragment [Pd(eta(3)-2-Me-C(3)H(4))(S)(2)](+), S = acetone, reacts in acetone with Me-TPzT or Br-TPzT in a 3:1 molar ratio to generate new complexes in which two allylpalladium fragments are present and the TPzT ligands have been partially hydrolyzed: [{Pd(eta(3)-C(4)H(7))}(2)(X-BPzTO)]A, X-BPzTO = 4,6-bis[4-methyl(or bromo)pyrazol-1-yl]-1,3,5-triazin-2-olate (X = Me, A = BF(4), 1; A = PF(6), 2; A = CF(3)SO(3), 3; A = p-MeC(6)H(4)SO(3), 4; X = Br, A = CF(3)SO(3), 5). When the ligand Me-BPzTOMe is made to react with only 1 equiv of the palladium solvate, compound 6, [Pd(eta(3)-2-Me-C(3)H(4))(Me-BPzTOMe)]CF(3)SO(3), is isolated. Reaction of 6 with another 1 equiv of the palladium derivative leads to 3. The intermediate 7, [{Pd(eta(3)-2-Me-C(3)H(4))}(2)(Me-BPzTOMe)]CF(3)SO(3), has been isolated as an almost pure compound. The reaction of Me-BPzTOMe with 1 equiv of [Pd(C(6)F(5))(2)(cod)] (cod = 1,5-cyclooctadiene) leads to the complex [Pd(C(6)F(5))(2)(Me-BPzTOMe)], 8. Attention has been focused on the dynamic behavior, related with metallotropic phenomena, of the new complexes. (1)H NMR variable-temperature studies of complexes 1, 6, and 8 have been carried out. For 8, only one static species is observed, while, for 1 and 6, two isomers are detected at low temperature. Different DeltaG(c)() activation energies at the coalescence temperature have been determined and are ascribed to processes implying Pd-N bond ruptures. For 6, two different barriers are detected, corresponding to Pd-N(triazine) or Pd-N(pyrazole) bond ruptures. From the DeltaG(c)() data, it is concluded that the main driving force of the hydrolysis process is the formation of a better coordinating ligand. The molecular structure of 4 has been determined by X-ray diffraction. The meso isomer, in which the two C-Me axes of the allylic groups are oriented in the same direction, is found in the solid state.

Partial removal of chloride anions from the dimer [Pd(η3-2-CH3-C3H4)(µ-Cl)]2 with AgTf(Tf = CF3SO3) followed by addition of dppm affords [Pd2(η3-Me-C3H4)2(μ-Cl)(μ-dppm)]Tf (1). The substitution of Cl− by X − (X = pz, SC6F5, Spy using the appropriate salts yields the new derivatives [Pd2(η3-Me-C3H4)2(μ-X)(μ-dppm)]Tf (2–4). All complexes exhibit a dinuclear half-A-frame structure with two isomers present in solution. The isomers differ in the relative orientation of the two allyl groups (cis or trans). The isomer interconversion was studied by variable temperature 1H NMR spectroscopy. The molecular structures of 2 and 4 were solved by X-ray diffraction studies. A distorted boat conformation of the seven- or six-membered metallacycle was found in both cases.