Rock-magnetic properties of topsoils and urban dust from Morelia (>800,000 inhabitants), Mexico: Implications for anthropogenic pollution monitoring in Mexico’s medium size cities

En el presente trabajo, investigamos la correlación entre algunos parámetros magnéticos y el nivel de contaminación por metales pesados en suelos urbanos de la ciudad de Morelia, en el occidente de México. El estudio magnético fue llevado a cabo en 98 muestras urbanas provenientes de diferentes tipos de uso de suelo. La mayoría de las muestras contienen minerales ferrimagnéticos como responsables de la magnetización, pertenecientes probablemente a las soluciones sólidas de las titanomagnetitas/ titanomaghemitas. Esto es inferido a partir de las mediciones de susceptibilidad en función de la temperatura y de los experimentos de magnetización remanente isotérmica (MRI). Estas mediciones indican además, que la mayoría de las muestras se saturan casi completamente antes de los 300 mT. Adicionalmente, los valores S-200 (S-200 = IRM-200/SIRM, donde IRM-200= magnetización a campo inverso de 200 mT después de la saturación magnética) se encuentran entre 0.7 y 1.0, característicos de minerales de baja coercitividad magnética. Las curvas promedio de magnetización remanente isotérmica de saturación (SIRM) pueden ser usadas como un indicador del nivel de contaminación, ya que estas curvas muestran diferentes valores de saturación de acuerdo al nivel de contaminación por metales pesados: Cu, Ni, Cr y Sr. Estas asociaciones de (titano)magnetitas con metales pesados fueron observadas bajo el Microscopio Electrónico de Barrido, revelando algunos agregados complejos en lugar de las esférulas detectadas comúnmente.In this work, we investigate the correlation between some magnetic parameters and the level of contamination by heavy metals in urban soils from Morelia city, western Mexico. The magnetic study was carried out on 98 urban soils samples belonging to distinct land uses. Most of analyzed samples contain ferrimagnetic minerals as the responsible for magnetization, most probably corresponding to the titanomagnetites/titanomaghemites solid solutions. This is inferred from the susceptibility vs. temperature measurements and the isothermal remanent magnetization (IRM) experiments. These measurements also indicate that most of samples are almost completely saturated before 300 mT. Additionally, the S-200 values (S-200 = IRM-200/ SIRM, where IRM-200= Back-field of 200 mT after magnetic saturation) are between 0.7 and 1.0, characteristic of low coercivity magnetic minerals. The averaged saturation isothermal remanent magnetization (SIRM) curves can be used as an indicator of pollution level, as these curves show different saturation values according to the level of contamination by heavy metals: Cu, Ni, Cr and Sr. These associations of (titano)magnetite with heavy metals were observed by Scanning Electron Microscope revealing some complex aggregates rather than commonly detected spherules.Universidad Nacional Autónoma de México through the projects CONACYT 118971 and PAPIIT IN 22311

Kinetic investigations of quaternization reactions of poly[2‐(dimethylamino)ethyl methacrylate] with diverse alkyl halides

Abstract Kinetic investigations of the quaternization reactions of poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) with alkyl halides (1‐iodobutane, 1‐iodoheptane, and 1‐iododecane) are carried out at different temperatures. For this purpose, a PDMAEMA ( M n = 17.8 kDa, Ð = 1.35) synthesized via reversible addition fragmentation chain transfer polymerization is utilized. The progress of the quaternization reactions is followed by proton nuclear magnetic resonance. As expected, the rate of quaternization is higher with increasing temperature. The experimental data are used to determine the following kinetic parameters: order of the reaction, Arrhenius' pre‐exponential factor, and activation energy. To the best of knowledge, this is the first contribution that provides detailed kinetic data of the quaternization reactions on PDMAEMA

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

La escultura arquitectónica modelada en estuco de Calakmul, Campeche, México: la transformación material en el proceso tecnológico

The stucco architectural sculpture of the frieze of the structure Sub IIC-1 of the archaeological site of Calakmul, Campeche, México, is a paradigmatic case study for understanding the origins of a city that became a regional capital of the Maya Lowlands. In particular, the identification of materials and techniques of each of the stages for the construction of this relief demonstrate that craft specialization derived from both the knowledge on the local exploitation of materials and a technological tradition shared with other Pre-Classic sites of the Peten region.La escultura arquitectónica elaborada en estuco del friso de la estructura Sub IIC-1 del sitio arqueológico de Calakmul, Campeche, México, constituye un caso de estudio paradigmático para entender los orígenes de una urbe que se convirtió en una de las capitales regionales más destacadas de la cultura Maya de las Tierras Bajas. En particular, la caracterización de los materiales y de las técnicas empleadas en cada una de las etapas de elaboración de este relieve escultórico demuestra que la especialización en la manufactura deriva tanto de un conocimiento pleno sobre la explotación local de la materia prima como de una tradición tecnológica compartida con otros sitios Preclásicos de la región del Petén

Platinum-Decorated TiO₂: One Step Fast Monometallic Impregnation and Plasma Effect on Nanoparticles

In the present work, N-TiO2−x/Pt was synthesized using a homemade nitrogen plasma (AC) discharge system. The overall procedure use of low-power nitrogen plasma (100 watts) with 1 and 2 h of plasma discharge to successfully impregnate platinum nanoparticles on P25 titanium dioxide. The obtained samples were characterized using X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM). The results reveal the incorporation of metallic Pt up to 2.9% on the surface of TiO2 by increasing the duration of plasma discharge by up to two hours with a constant power of 100 watts. Likewise, the incorporation of nitrogen atoms into a lattice crystal was also favored, confirming a direct relationship between the amount of Pt and nitrogen atoms introduced in TiO2 as a function of the duration of plasma treatment. By characterizing nanoparticles loaded on a N-TiO2−x/Pt surface, we show that joined platinum nanoparticles have two different patterns, and the boundary between these two regions coalesces. The results demonstrate that the use of nitrogen plasma to impregnate platinum nanoparticles on the surface of TiO2 to obtain N-TiO2−x/Pt allows wide and relevant physics and chemistry applications

Chemical Interactions in Reinforced Concrete Exposed at a Tropical Marine Environment

Prediction of concrete structure behavior is complicated by diverse factors, including interaction between elements and concrete compounds, chlorides diffusion through concrete, and compounds formed by corrosion of steel reinforcement. These factors were evaluated in concrete test cylinders exposed to a tropical marine environment since 1993 (during 126 months). Electrochemical, chlorides profile, scanning electron microscope, and energy-dispersive X-ray spectrophotometry analyses were done and results compared. This suite of analytical methods accurately characterized reinforced concrete condition and generated data useful in developing prediction models of corrosion in concrete structures

Weathering Effects of an Historic Building in San Francisco de Campeche, México

Este trabajo presenta una descripción cualitativa del fenómeno de degradación que ha ocurrido en los muros externos del bastión de San Carlos, una estructura militar construida con material calcáreo entre los siglos XVI y XVII en la ciudad colonial de San Francisco de Campeche, México. Se identificaron varias estructuras debidas al intemperismo en los morteros y las piedras calizas. Se realizaron análisis mediante microscopía electrónica de barrido (sem/eds), difracción de rayos X (xrd) y microscopía óptica (om) para determinar la naturaleza de los compuestos formados. Los resultados indican que el clima tropical provoca efectos físicos, químicos y biológicos en los materiales de construcción, principalmente debidos a la disponibilidad de agua. La influencia de esta disponibilidad de agua parece ser la causa fundamental de los daños observados en el edificio, por encima de la acción de las sales marinas o los contaminantes atmosféricos. Se observó la formación de costras ricas en carbonato de calcio, debidas al proceso de disolución y recristalización acrecentado por la abundante presencia de agua. También se identificaron neominerales como whewellita y wheddelita, relacionadas con la actividad microbiana. La presencia de elementos como cloro, sodio y azufre indican que la degradación del edificio ocurrió mediante procesis sinérgicos durante su larga exposición al ambiente tropical de San Francisco de Campeche

Kinetic Investigations of Quaternization Reactions of Poly[2‐(dimethylamino)ethyl methacrylate] with Diverse Alkyl Halides

Abstract Kinetic investigations of the quaternization reactions of poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) with alkyl halides (1‐iodobutane, 1‐iodoheptane, and 1‐iododecane) are carried out at different temperatures. For this purpose, a PDMAEMA ( M n = 17.8 kDa, Ð = 1.35) synthesized via reversible addition fragmentation chain transfer polymerization is utilized. The progress of the quaternization reactions is followed by proton nuclear magnetic resonance. As expected, the rate of quaternization is higher with increasing temperature. The experimental data are used to determine the following kinetic parameters: order of the reaction, Arrhenius' pre‐exponential factor, and activation energy. To the best of knowledge, this is the first contribution that provides detailed kinetic data of the quaternization reactions on PDMAEMA