Analysis of Trace Impurities in Lithium Carbonate.

Lithium carbonate (Li2CO3) is a critical raw material in cathode material production, a core of Li-ion battery manufacturing. The quality of this material significantly influences its market value, with impurities potentially affecting Li-ion battery performance and longevity. While the importance of impurity analysis is acknowledged by suppliers and manufacturers of battery materials, reports on elemental analysis of trace impurities in Li2CO3 salt are scarce. This study aims to establish and validate an analytical methodology for detecting and quantifying trace impurities in Li2CO3 salt. Various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), were employed to analyze synthetic and processed lithium salt. X-ray diffraction patterns of Li2CO3 were collected via step-scanning mode in the 5-80° 2θ range. SEM-EDX was utilized for particle morphology and quantitative impurity analysis, with samples localized on copper tape. XPS equipped with a hemispherical electron analyzer was employed to analyze the surface composition of the salt. For ICP-OES analysis, a known amount of lithium salt was subjected to acid digestion and dilution with ultrapure water. Multielemental standard solutions were prepared, including elements such as Al, Cd, Cu, Fe, Mn, Ni, Pb, Si, Zn, Ca, K, Mg, Na, and S. Results confirmed the presence of the zabuyelite phase in XRD analysis, corresponding to the natural form of lithium carbonate. SEM-EDX mapping revealed impurities of Si and Al, with low relative quantification values of 0.12% and 0.14%, respectively. XPS identified eight potential impurity elements, including S, Cr, Fe, Cl, F, Zn, Mg, and Na, alongside Li, O, and C. Regarding ICP-OES analysis, performance parameters such as linearity, limit of detection (LOD), and quantification (LOQ), variance, and recovery were evaluated for analytical validation. ICP-OES results demonstrated high linearity (>0.99), with LOD and LOQ values ranging from 0.001 to 0.800 ppm and 0.003 to 1.1 ppm, respectively, for different elements. The recovery rate exceeded 90%. In conclusion, the precision of the new ICP-OES methodology renders it suitable for identifying and characterizing Li2CO3 impurities. It can effectively complement solid-state techniques such as XRD, SEM-EDX, and XPS.

Exploring the Influence of Cation and Halide Substitution in the Structure and Optical Properties of CH3NH3NiCl3 Perovskite.

This manuscript details a comprehensive investigation into the synthesis, structural characterization, thermal stability, and optical properties of nickel-containing hybrid perovskites, namely CH3NH3NiCl3, CsNiCl3, and CH3NH3NiBrCl2. The focal point of this study is to unravel the intricate crystal structures, thermal behaviors, and optical characteristics of these materials, thereby elucidating their potential application in energy conversion and storage technologies. X-ray powder diffraction measurements confirm that CH3NH3NiCl3 adopts a crystal structure within the Cmcm space group, while CsNiCl3 is organized in the P63/mmc space group, as reported previously. Such structural diversity underscores the complex nature of these perovskites and their potential for tailored applications. Thermal analysis further reveals the stability of CH3NH3NiCl3 and CH3NH3NiBrCl2, which begin to decompose at 260 °C and 295 °C, respectively. The optical absorption properties of these perovskites studied by UV-VIS-NIR spectroscopy revealed the bands characteristic of Ni2+ ions in an octahedral environment. Notably, these absorption bands exhibit subtle shifts upon bromide substitution, suggesting that optical properties can be finely tuned through halide modification. Such tunability is paramount for the design and development of materials with specific optical requirements. By offering a detailed examination of these properties, the study lays the groundwork for future advancements in material science, particularly in the development of innovative materials for sustainable energy technologies.

The importance of the pretreatment of samples in Nd quantification from NdFeB magnets through inductively coupled plasma atomic emission spectroscopy (ICP-OES)-a rapid and streamlined methodology.

In this study, we emphasize the critical role of sample pretreatment. We report on the behavior of NdFeB magnet samples exposed to four different acid media for digestion. NdFeB magnets are becoming a significant source of neodymium, a rare-earth element critical to many technologies and a potential substitute for traditional mining of the element. To address this, we meticulously tested nitric acid, hydrochloric acid, acetic acid, and citric acid, all at a concentration of 1.6 M, as economical and environmentally friendly alternatives to the concentrated mineral acids commonly used in the leaching of these materials. The pivotal stage involves the initial characterization of samples in the solid state using SEM-EDX and XPS analysis to obtain their initial composition. Subsequently, the samples are dissolved in the four aforementioned acids. Finally, neodymium is quantified using ICP-OES. Throughout our investigation, we evaluated some analytical parameters to determine the best candidate for performing the digestion, including time, limits of detection and quantification, accuracy, recovery of spike samples, and robustness. After careful consideration, we unequivocally conclude that 1.6 M nitric acid stands out as the optimal choice for dissolving NdFeB magnet samples, with the pretreatment of the samples being the critical aspect of this report.

Characterization of biofilm formation by Exiguobacterium strains in response to arsenic exposure.

IMPORTANCE: In this work, we characterized the composition, structure, and functional potential for biofilm formation of Exiguobacterium strains isolated from the Salar de Huasco in Chile in the presence of arsenic, an abundant metalloid in the Salar that exists in different oxidation states. Our results showed that the Exiguobacterium strains tested exhibit a significant capacity to form biofilms when exposed to arsenic, which would contribute to their resistance to the metalloid. The results highlight the importance of biofilm formation and the presence of specific resistance mechanisms in the ability of microorganisms to survive and thrive under adverse conditions.

Synthesis, Characterization, and Photoelectric and Electrochemical Behavior of (CH3NH3)2Zn1-xCoxBr4 Perovskites.

We report the synthesis, characterization, and photoelectric and electrochemical properties of (CH3NH3)2Zn1-xCoxBr4 (x = 0.0, 0.3, 0.5, 0.7, and 1.0) samples. X-ray powder and single-crystal diffraction confirm the formation of solid solution across the entire range. Additionally, as the cobalt concentration increases, the crystallinity of the samples decreases, as indicated by the powder diffraction patterns. All samples remain stable up to 560 K, beyond which they decompose into CH3NH3Br and the respective bromide. The semiconductor behavior of the compounds is confirmed through optical absorption measurements, and band gap values are determined by using the Tauc method from diffuse reflectance spectra. Raman spectroscopy reveals a slight redshift in all vibration modes with increasing cobalt content. Finally, photovoltaic measurements on solar cells constructed with (MA)2CoBr4 perovskite exhibit modest performance, and electrochemical measurements indicate that the compound with the composition (MA)2Zn0.3Co0.7Br4 exhibits the highest current for electrochemical water reduction during oxygen evolution.

Response to Static Magnetic Field-Induced Stress in Scenedesmus obliquus and Nannochloropsis gaditana.

Magnetic fields in biological systems is a promising research field; however, their application for microalgae has not been fully exploited. This work aims to measure the enzymatic activity and non-enzymatic activity of two microalgae species in terms of superoxide dismutase (SOD), catalase (CAT), and carotenoids, respectively, in response to static magnetic fields-induced stress. Two magnet configurations (north and south) and two exposure modes (continuous and pulse) were applied. Two microalgae species were considered, the Scenedesmus obliquus and Nannochloropsis gaditana. The SOD activity increased by up to 60% in S. obliquus under continuous exposure. This trend was also found for CAT in the continuous mode. Conversely, under the pulse mode, its response was hampered as the SOD and CAT were reduced. For N. gaditana, SOD increased by up to 62% with the south configuration under continuous exposure. In terms of CAT, there was a higher activity of up to 19%. Under the pulsed exposure, SOD activity was up to 115%. The CAT in this microalga was increased by up to 29%. For N. gaditana, a significant increase of over 40% in violaxanthin production was obtained compared to the control, when the microalgae were exposed to SMF as a pulse. Depending on the exposure mode and species, this methodology can be used to produce oxidative stress and obtain an inhibitory or enhanced response in addition to the significant increase in the production of antioxidant pigments.

Correction to: A thiotrophic microbial community in an acidic brine lake in Northern Chile.

In Table 1 of the original article, the unit mg/L was incorrectly published as ng/L in the aluminum, chloride, sulphate and OM columns.

A thiotrophic microbial community in an acidic brine lake in Northern Chile.

The endorheic basins of the Northern Chilean Altiplano contain saline lakes and salt flats. Two of the salt flats, Gorbea and Ignorado, have high acidic brines. The causes of the local acidity have been attributed to the occurrence of volcanic native sulfur, the release of sulfuric acid by oxidation, and the low buffering capacity of the rocks in the area. Understanding the microbial community composition and available energy in this pristine ecosystem is relevant in determining the origin of the acidity and in supporting the rationale of conservation policies. Besides, a comparison between similar systems in Australia highlights key microbial components and specific ones associated with geological settings and environmental conditions. Sediment and water samples from the Salar de Gorbea were collected, physicochemical parameters measured and geochemical and molecular biological analyses performed. A low diversity microbial community was observed in brines and sediments dominated by Actinobacteria, Algae, Firmicutes and Proteobacteria. Most of the constituent genera have been reported to be either sulfur oxidizing microorganisms or ones having the potential for sulfur oxidation given available genomic data and information drawn from the literature on cultured relatives. In addition, a link between sulfur oxidation and carbon fixation was observed. In contrast, to acid mine drainage communities, Gorbea microbial diversity is mainly supported by chemolithoheterotrophic, facultative chemolithoautotrophic and oligotrophic sulfur oxidizing populations indicating that microbial activity should also be considered as a causative agent of local acidity.

Definición del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) / Definition of obstructive sleep apnea-hypopnea syndrome (OSAHS)

Resumen El síndrome de apnea-hipopnea obstructiva del sueño es uno de los trastornos del sueño más prevalentes en la población general y está asociado a diferentes alteraciones biológicas que pueden llegar a desencadenar importantes problemas cognitivos, metabólicos y cardiovasculares. Este artículo está dedicado a su definición y a proporcionar los criterios diagnósticos mínimos, tanto clínicos como polisomnográficos, que se tienen en la actualidad.

Abstract Obstructive sleep apnea-hypopnea syndrome (OSAHS) is one of the most prevalent sleep disorders in the general population, and is associated with different biological alterations that can trigger important cognitive, metabolic and cardiovascular problems. This article aims at defining and providing the minimum diagnostic criteria, both clinical and polysomnographic, currently in use.

Historia del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) / History of obstructive sleep apnea-hypopnea syndrome (OSAHS)

Resumen La historia de la apnea obstructiva del sueño es larga y complicada desde sus primeras descripciones en el siglo XIX con el relato de Pickwick en la primera novela de Charles Dickens. La definición de este término por parte de diferentes investigadores resalta la importancia de comprender las entidades asociadas al síndrome, como la hipoventilación alveolar y la somnolencia diurna excesiva. De esta forma, los estudios neurofisiológicos adelantados desde entonces, el desarrollo de la conferencia de la sociedad europea de neurología de 1964, la descripción del síndrome en pacientes pediátricos, la confirmación de la comorbilidad cardiovascular asociada a la enfermedad, la traqueostomía como tratamiento y la creación de implantes de estimuladores del nervio hipogloso -pasando por el descubrimiento de Sullivan de la presión positiva como tratamiento en casa- han sido esenciales para la comprensión de este síndrome.

Abstract The history of obstructive sleep apnea is long and complicated, and some descriptions can be traced back to the early nineteenth century in The Posthumous Papers of the Pickwick Club, the first novel written by Charles Dickens. The definition of this term by different researchers highlights the importance of understanding the entities associated with the syndrome, such as alveolar hypoventilation and excessive daytime sleepiness. Thus, the neurophysiological studies carried out since then, as well as the European Society of Neurology conference held in 1964, the description of the syndrome in pediatric patients, the confirmation of cardiovascular co-morbidity associated with the disease, tracheostomy as treatment and the creation of hypoglossal nerve stimulus implants -including Sullivan's discovery of positive pressure as a home treatment- have been essential for the understanding of this syndrome.

Cuadro clínico del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) / Clinical picture of obstructive sleep apnea-hypopnea syndrome (OSAHS)

Resumen El pilar para el diagnóstico del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) es el cuadro clínico obtenido mediante una historia clínica detallada. Los síntomas son referidos por el paciente o su compañero de cama y se pueden dar durante el sueño o la vigilia; estos últimos se presentan como consecuencia del trastorno del sueño. Los síntomas son consecuencia de la obstrucción de la vía aérea superior, de la hipoxia intermitente o de la fragmentación repetida del sueño. Para el diagnóstico de SAHOS, se deben tener en cuenta los factores agravantes, las comorbilidades, los antecedentes familiares, el examen físico, la obtención de medidas antropométricas, los signos vitales y los hallazgos anatómicos estructurales asociados con este síndrome o con alteraciones congénitas que lo predispongan. Tener conocimiento de estos aspectos clínicos es fundamental para alcanzar una buena aproximación a su diagnóstico.

Abstract The baseline for the diagnosis of obstructive sleep apnea-hypopnea syndrome (OSAHS) is the clinical picture obtained through a detailed clinical history. The symptoms are referred by the patients or their bed partners, can occur during sleep or wakefulness, and are a consequence of sleep disorders. Upper airway obstruction, intermittent hypoxia, or repeated sleep fragmentation are the cause of the symptoms. For the diagnosis of OSAHS, aggravating factors, comorbidities, family history, physical examination, anthropometric measurements, vital signs and structural anatomical findings associated with this syndrome or with predisposing congenital abnormalities should be taken into account. Knowing these clinical aspects is fundamental to reach a good approximation to diagnosis.

Tratamiento médico del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) / Medical treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS)

Resumen El tratamiento de síndrome de apnea obstructiva del sueño busca solucionar los signos y síntomas relacionados con la enfermedad, así como la reducción del índice de apnea-hipopnea y las desaturaciones, para así disminuir los riesgos y comorbilidades vinculados a este trastorno. Sin embargo, esta enfermedad requiere tratamiento a largo plazo, con terapias combinadas y desarrolladas por un equipo multidisciplinario. El tratamiento médico se debe realizar en todos los pacientes, aun si se requieren terapias adicionales. Asimismo, este síndrome se puede asociar a otras enfermedades que necesitan tratamiento específico.

Abstract The treatment of the obstructive sleep apnea syndrome (OSAHS) seeks to solve the signs and symptoms related to the disease, as well as to reduce the apnea-hypopnea index (AHI) and the desaturations, to achieve a decrease of associated risks and comorbidities. However, this disease requires long-term treatment, with combined therapies developed by a multidisciplinary team. Medical treatment should be performed on all patients, even if additional therapies are necessary. In addition, this syndrome may be associated with other diseases that need specific treatment.

The Ecological Coherence of Temperature and Salinity Tolerance Interaction and Pigmentation in a Non-marine Vibrio Isolated from Salar de Atacama.

The occurrence of microorganisms from the Vibrio genus in saline lakes from northern Chile had been evidenced using Numerical Taxonomy decades before and, more recently, by phylogenetic analyses of environmental samples and isolates. Most of the knowledge about this genus came from marine isolates and showed temperature and salinity to be integral agents in shaping the niche of the Vibrio populations. The stress tolerance phenotypes of Vibrio sp. Teb5a1 isolated from Salar de Atacama was investigated. It was able to grow without NaCl and tolerated up to 100 g/L of the salt. Furthermore, it grew between 17° and 49°C (optimum 30°C) in the absence of NaCl, and the range was expanded into cold temperature (4-49°C) in the presence of the salt. Other additional adaptive strategies were observed in response to the osmotic stress: pigment production, identified as the known antibacterial prodigiosin, swimming and swarming motility and synthesis of a polar flagellum. It is possible to infer that environmental congruence might explain the cellular phenotypes observed in Vibrio sp. considering that coupling between temperature and salinity tolerance, the production of antibacterial agents at higher temperatures, flagellation and motility increase the chance of Vibrio sp. to survive in salty environments with high daily temperature swings and UV radiation.

Guía para la certificación de servicios diagnósticos de trastornos del sueño en Colombia (Incluye estándares para Servicios Pediátricos) / Guidelines for the voluntary certification of services studying sleep disorders in Colombia (including standards for paediatric services)

Antecedentes. La Asociación Colombiana de Sociedades Científicas (ACSC) convocó al Grupo de Investigación Transdisciplinario en Trastornos del Sueño (GITTS) -conformado por la Asociación Colombiana de Medicina del Sueño (ACMES), la Asociación Colombiana de Medicina Interna (ACMI®-Médicos para adultos), la Asociación Colombiana de Neumología y Cirugía de Tórax (Asoneumocito), la Asociación Colombiana de Neurología (ACN), la Asociación Colombiana de Otorrinolaringología y Cirugía Plástica Facial (ACORL) y la Asociación Colombiana de Psiquiatría (ACP)- para que elaboraran un documento con el cual se estableciera una normatividad para la certificación voluntaria de los servicios que estudian los trastornos del sueño en Colombia. Se busca que este proceso fomente la excelencia en el diagnóstico de los trastornos del sueño. Objetivos. El proceso busca definir los estándares mínimos para los servicios diagnósticos de medicina del sueño en Colombia. Aunque riguroso, el proceso ha de ser "amigable para el usuario". Se propone a la ACMES como ente evaluador. Materiales y métodos. El proceso evalúa la organización y administración de los servicios, los empleados y la dirección, las políticas y los procedimientos, la educación y el desarrollo del personal, las instalaciones y los equipos, así como el aseguramiento de la calidad. El enfoque general estuvo influenciado por programas establecidos y adoptados en otros países. Se espera que la consistencia con las guías internacionales disminuya la cantidad de trabajo necesaria para preparar la aplicación para los servicios que ya estén involucrados en los procedimientos de certificación -por ejemplo, certificación de hospitales- y que esto ayude a preparar el camino para la certificación en sueño. Resultados. La primera fase del proceso incluye contestar un cuestionario detallado designado para evaluar qué tan preparado está el servicio para ser certificado. La autoevaluación es una característica clave de esta fase. La habilidad para responder satisfactoriamente el cuestionario, guiado por los Estándares de Certificación detallados más adelante, deberá indicar al servicio solicitante su capacidad para cumplir con los requisitos de certificación. Si las respuestas son satisfactorias, el servicio enviará una solicitud completa. Si el Comité Evaluador (ACMES) establece que la solicitud llena los estándares, se realizará una visita a las instalaciones. Los servicios que evalúan niños menores de 12 años, deben cumplir con los requisitos específicos para esta población. Los mayores de 12 años sin condiciones médicas complejas se pueden estudiar en servicios certificados para adultos, siempre y cuando, disponga de los equipos de reanimación y de personal entrenado.

Background. The Colombian Association of Scientific Societies (known as ACSC in Spanish) requested the Transdisciplinary Research Group on Sleep Disorders (GITTS) to prepare a document establishing regulations for the voluntary certification of services studying sleep disorders in Colombia. The GITTS was formed by the Colombian Association of Sleep Medicine (ACMES), the Colombian Association of Internal Medicine (ACMI), the Colombian Association of Pneumology and Thoracic Surgery (Asoneumocito), the Colombian Association of Neurology (ACN), the Colombian Association of Otorhinolaryngology and Facial Plastic Surgery (ACORL) and the Colombian Association of Psychiatry (ACP). It was intended that this exercise would promote excellence in diagnosing sleep disorders. Objectives. Defining minimum standards for assessing/evaluating sleep disorder diagnosis services in Colombia; although rigorous, they had to be user-friendly. ACMES was proposed to play the role of guidelines controller. Materials and methods. The exercise evaluated service organisation and management, employees and management, policy and procedures, education and staff development, facilities and equipment and quality assurance. The overall approach was influenced by programmes already established and adopted by other countries. It was expected that uniformity regarding international guidelines would decrease the amount of work needed for preparing documentation for services which are already involved in certification procedures, for example, hospital certification, and that this would help pave the way for sleep medicine certification. Results. The first step involved a self-questionnaire designed to assess whether a particular service was ready to be certified, self-assessment being a key feature of this phase. Successfully responding to the questionnaire (guided by the certification standards) indicated whether a particular sleep disorder service met certification requirements. If the answers were satisfactory, then such service would send in a complete application. A site visit would then be made if the evaluation committee (ACMES) stated that the full standards had been satisfactorily met. Services assessing children under 12 years-old had to meet specific requirements for such population. Children over 12 years-old who did not have a complex medical condition could be studied by certified adult services, as long as resuscitation equipment and trained personnel were available.