A method for the separation of paramagnetic, ferrimagnetic and haematite magnetic subfabrics using high-field torque magnetometry

In this study, the contribution of the paramagnetic, ferrimagnetic and haematite components to the magnetic anisotropy is separated by means of high-field torque magnetometry. Torque measurements at different fields, which are high enough to saturate the ferrimagnetic minerals, however, still low enough that the torque resulting from the haematite is linear with field, allow for the separation of the three magnetic anisotropy components. The method has been applied to haematite single crystals in which no paramagnetic or ferrimagnetic components have been found contribute to the torque signal. The mean direction of the poles to the crystallographic basal plane in the haematite single crystals is subparallel to the minimum-susceptibility direction measured in low-field. The separation analysis has also been applied to highly deformed red beds from the Lower Glarus nappe complex (Switzerland). No ferrimagnetic phases are present in the rocks and, therefore, they cannot contribute to the anisotropy of magnetic susceptibility. The magnetic fabric arises from a paramagnetic subfabric carried by the phyllosilicate minerals and haematite, in which the basal planes of both phases are in the cleavage plane. The measured magnetic lineation seen in low-field anisotropy of magnetic susceptibility appears to be an apparent lineation that arises from a weak girdling of haematite and the paramagnetic minerals conforming the roc

Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Lowerature magnetization of hematite within the basal plane has been studied in a collection of natural crystals by means of torque magnetometry. Comparison between the torque curves at room temperature and at 77 K allows identification of a weak ferromagnetic moment constrained within the basal plane at temperatures well below the Morin transition. Annealing the samples produces the expected reduction of the weak ferromagnetic moment, but there is also a relationship between the ferromagnetic moment before and after annealing. Lowerature measurements after the annealing experiment reveal the presence of a weak ferromagnetic moment that survives the annealing. This observation suggests the magnetic structure of natural hematite crystals below the Morin transition can still be a carrier of magnetization. Key Points A weak ferromagnetic (WFM) moment is detected below the Morin transition The WFM lies within the basal plane Natural Hematite is not a pure AF below TM ©2013. American Geophysical Union. All Rights Reserved.Peer Reviewe

A rock magnetic profile through the ejecta flap of the Lockne impact crater (central Sweden) and implications for the impact excavation process

The well-documented, well-preserved, and well-exposed Lockne crater is a reference crater for marine-target impacts on Earth. The large amount of data allows detailed analysis of the cratering and modification processes. A unique feature of Lockne as compared with other similar craters is its pristine ejecta layer. Here, we provide the first complete lithological description coupled with an analysis of the rock magnetic properties of the Lockne-9 core drilled through the ejecta flap. Low-field bulk magnetic susceptibility, magnetic hysteresis, isothermal remanent magnetization curves (IRM), and the corresponding model of the coercivity spectra, backfield IRM, and thermomagnetic curves are used to fully characterize the magnetic mineralogy (i.e., pseudo-single domain (PSD) magnetite and pyrite). Variation of the magnetic properties with depth reveals a characteristic maximum in the magnetic susceptibility and magnetization within the crystalline ejecta. The magnetic properties of rocks affected by the impact show a slight weakening in the coercivity of magnetic minerals in comparison with rocks not affected by the impact Altogether, this suggests to us that the high magnetization zone already existed before the impact event took place. Therefore, it can be inferred that during the cratering process, the Lockne ejecta was repositioned en masse from the central part of the crater in the form of an ejecta flap. This stands in contrast to the standard ballistic emplacement model wherein individual particles move in an ejecta curtain

Separation of diamagnetic and paramagnetic anisotropy by high-field, low-temperature torque measurements

The anisotropy of magnetic susceptibility (AMS) of rocks can be composed of contributions from ferromagnetic, paramagnetic and diamagnetic minerals. However, in general the AMS of only one fraction is of interest. While there are several approaches to isolate the ferromagnetic contribution to the AMS, the separation of the diamagnetic from the paramagnetic contribution is still problematic. A new method for the separation of these two contributions based on high-field torque measurements at room and low-temperature is presented. The paramagnetic anisotropy increases at low temperature according to the Curie-Weiss law, whereas the diamagnetic contribution is temperature independent. If the paramagnetic AMS is due to perfectly oblate or prolate minerals and the ratio of the susceptibility differences at two temperatures is known, paramagnetic and diamagnetic AMS can be separated. When measuring in fields high enough to saturate the ferromagnetic phases all three contributions to the AMS can be separated. The separation of paramagnetic and diamagnetic AMS is demonstrated on natural crystals and synthetic calcite-muscovite aggregates. A high-field torque magnetometer, equipped with a cryostat for measurements at 77 K, allows sensitive measurements at two different temperatures. The sensitivity at 77 K is 3 × 10−7 J and standard-sized (palaeomagnetic) samples of 11.4 cm3 can be measured. This new method is especially suited for the investigation of diamagnetic fabrics of impure carbonate rock

Estrategias de mercadotecnia de MIPyMEs durante la pandemia COVID-19 en Ciudad Juárez, Chihuahua, México

El objetivo de esta investigación fue identificar las estrategias de mercadotecnia utilizadas por las MIPYMEs durante la pandemia Covid-19 en Ciudad Juárez, Chihuahua. Para ello, se utilizó una metodología cuantitativa, de diseño no experimental transeccional descriptivo. Se consideró como unidad de análisis a micro, pequeñas y medianas empresas de los sectores comercial, servicios e industrial, establecidas en Ciudad, Juárez, Chihuahua. La recolección de información se realizó a través del método de encuesta, se administró un cuestionario validado previamente por un grupo de expertos. El cuestionario se distribuyó a través de redes sociales y correo electrónico, fue dirigido al administrador general de la empresa y se recolectaron 39 cuestionarios. Los resultados obtenidos muestran que las MIPyMEs, modificaron y/o adaptaron su producto o servicio para cubrir las necesidades del consumidor, e incrementaron la promoción a través de redes sociales, así mismo implementaron nuevos sistemas de distribución y medios de pago para alcanzar a su mercado meta.   The objective of this research was to identify the marketing strategies used by MSMEs during the Covid-19 pandemic in Ciudad Juarez, Chihuahua. A quantitative methodology was used for this purpose, with a descriptive transectional non-experimental design. Micro, small and medium-sized companies in the commercial, services and industrial sectors, established in Ciudad, Juarez, Chihuahua, were considered as the unit of analysis. The information collection was carried out through the survey method; a questionnaire form was used, previously validated by a group of experts. The questionnaire was distributed through social media and email, addressed to the general manager of the company, with a total of 39 questionnaires collected. The results obtained show that MSMEs modified and/or adapted their product or service to meet consumer needs and increased advertisement through social media, also implementing new distribution systems and payment options to reach their target market

Materias primas en las pastas cerámicas de origen volcánico en la cerámica canaria: descripción y caracterización geotécnica

[EN] The semi-artisanal weaving factory is a trade that has practically disappeared in the Canary Islands, and the production of earthenware is being conserved by a few potters who have shown their particular interest in maintaining the craft, and now their pieces are just decorative objects or souvenirs, far from the domestic use they used to have. The current generation uses a very similar terminology for raw materials, regardless of the island where they work. This is due to the fact that they consult the bibliographic sources about the last loceras of the Archipelago, to the greater communication between loceros/as because of the contact between themselves in insular handcraft fairs, or regional ones... as well as in promotion congresses organized by institutions. However, when ceramics were a livelihood in particular potters' centres of the Archipelago, the loceras called the materials according to the local terms transmitted to them by their predecessors, and the same term not always identified equal characteristics materials. In this work, ethnographic references on raw materials are collected, providing an overview and comparison of them, while an attempt of description of them has been tried by providing some more geotechnical data to facilitate the understanding of their behaviour in the ceramic processes.[ES] La tejería de producción semiartesanal es un oficio que está prácticamente desaparecido en el Archipiélago canario, y la producción de loza es conservada por unos pocos alfareros/as que han mostrado su interés particular por mantener el oficio, siendo sus piezas objetos decorativos o souvenirs alejándose del uso doméstico que antes cumplían. La generación actual emplea una terminología referente a las materias primas muy similar, independientemente de la Isla donde trabajen. Esto es debido a que consultan las fuentes bibligráficas sobre “las últimas loceras” del Archipiélago, a la mayor comunicación entre loceros/as gracias al contacto en ferias de artesanía insulares, regionales,... así como en jornadas de divulgación organizadas por instituciones. No obstante, cuando la cerámica era el medio de vida en los determinados focos alfareros del Archipiélago las loceras denominaban los materiales según los vocablos locales que les transmitían sus antecesoras, y no siempre el mismo término identificaba materiales de iguales características. En este trabajo se recopilan las referencias etnográficas sobre las materias primas aportando una visión de conjunto y comparativa de las mismas a la vez que se intentan describir aportando algunos datos de carácter más geotécnico que facilite el entendimiento sobre su comportamiento en los procesos cerámicos.Martín Afonso, C.; Acosta Hernández, F. (2021). Materias primas en las pastas cerámicas de origen volcánico en la cerámica canaria: descripción y caracterización geotécnica. En I Simposio anual de Patrimonio Natural y Cultural ICOMOS España. Editorial Universitat Politècnica de València. 121-130. https://doi.org/10.4995/icomos2019.2019.11696OCS12113

A modular and convergent synthetic route to supramolecular cyclic dimers based on Amidinium-Carboxylate interactions

We describe herein the optimized design and modular synthetic approach towards supramolecularly programmed monomers that can form discrete macrocyclic species of controllable size and shape through amidinium-carboxylate interactions in apolar and polar mediaFunding from MCIN (RED2018-102331-T, PID2020-116921GBI00, and TED2021-132602B-I00) and AEI (PID2020-116112RJ-I00) is gratefully acknowledged. F.A. is grateful to MCIN and Next Generation EU funding for a “Ramon-y-Cajal” fellowship (RyC2021-031538-I). I. L. M. and J.V. H. are grateful to MINECO for a FPI grant (PRE2018-085692) and to the Comunidad de Madrid for the PEJ-2021-AI/IND-22931 contract, respective

Oral cancer, HPV infection and evidence of sexual transmission

The incidence of oropharyngeal cancer and oral cancer is growing worldwide, both in young non-smokers and in young non-drinkers (smoking and drinking are considered the main risk factors). Epidemiologic studies suggest a strong association between the infection by human papillomavirus (HPV), especially types 16 and 18 (high oncological risk) which have already demonstrated their etiological role in anal tumours as well as in cervix cancer. There is clear epidemiologic evidence that both types of tumours relate to changes in sexual behaviour and that both are linked to sexual transmission of HPV. The number of oral and oropharyngeal cancer cases is rising nowadays, especially among young individuals with no typical toxic habits, such as tobacco and/or alcohol. In this review we set out to update the aspects related to the onset of oral cancer, its relationship with HPV infection and whether this association may be due to the sexual transmission of the virus

Comparative study of core-shell nanostructures based on amino-functionalized Fe-4@SiO2 and CoFe2O4@SiO2 nanocomposites

Fe3O4@SiO2 and CoFe2O4@SiO2 and their corresponding amino-functionalized nanocomposites were successfully synthesized by a process of two steps including the preparation by coprecipitation or hydrothermal synthesis of the corresponding magnetic cores, the coating of its surface with a silica coating followed by its subsequent functionalization with 3-aminopropyltriethoxysilane (APTES). All magnetic samples were characterized by XRD using FULPROFF program, FTIR analysis, TEM and M-H hysteresis loops. The results showed diffraction maxima indexed in a cubic symmetry of S. G. Fd-3m with Z = 8 compatible with an inverse spinel-type structure. FTIR spectra of all samples show the characteristic bands of the magnetic cores and others bands corresponding to the asymmetric vibration of O-Si-O and Si-O-Si bonds of silica. The TEM images confirm that all the nanoparticles are coated, finding the largest thickness of the coating in the Fe3O4 sample prepared hydrothermally, which are the smaller ones. An expected reduction of the saturation magnetization of the magnetic cores is achieved with the coating and functionalization, although the behaviour of the Fe3O4 -samples remains practically superparamagnetic while the corresponding ones of cobalt are still ferrimagnetic. Fe3O4 nanocomposites respond to more quickly in the presence of an external magnetic field, something important against the removal of contaminating species in aqueous media. UV-Vis spectroscopy studies confirm the adsorption capacity of Cu2+ in aqueous solutions of the prepared nanocomposites, having found that a small thickness of the coating leads a greater adsorption, so that the best adsorption is found for CPFe3O4@SiO2-APTES nanocomposite. (C) 2018 Elsevier B.V. All rights reserved

Unidad Técnica de Geodesia, Geofísica y Magnetismo de Rocas: Laboratorio de Paleomagnetismo, Magnetismo de Rocas y Modelado Geomagnético

Trabajo presentado en la I Reunión Científica del Instituto de Geociencias (CSIC-UCM), los días 15 y 16 de septiembre de 2011.Peer reviewe