Direct synthesis and chemical vapor deposition of 2D carbide and nitride MXenes.

Two-dimensional transition-metal carbides and nitrides (MXenes) are a large family of materials actively studied for various applications, especially in the field of energy storage. MXenes are commonly synthesized by etching the layered ternary compounds, called MAX phases. We demonstrate a direct synthetic route for scalable and atom-economic synthesis of MXenes, including compounds that have not been synthesized from MAX phases, by the reactions of metals and metal halides with graphite, methane, or nitrogen. The direct synthesis enables chemical vapor deposition growth of MXene carpets and complex spherulite-like morphologies that form through buckling and release of MXene carpet to expose fresh surface for further reaction. The directly synthesized MXenes showed excellent energy storage capacity for lithium-ion intercalation.

Hybrid organic-inorganic two-dimensional metal carbide MXenes with amido- and imido-terminated surfaces.

Two-dimensional (2D) transition-metal carbides and nitrides (MXenes) combine the electronic and mechanical properties of 2D inorganic crystals with chemically modifiable surfaces, which provides an ideal platform for both fundamental and applied studies of interfaces. Good progress has been achieved in the functionalization of MXenes with small inorganic ligands, but relatively little work has been reported on the covalent bonding of various organic groups to MXene surfaces. Here we synthesize a family of hybrid MXenes (h-MXenes) that incorporate amido- and imido-bonding between organic and inorganic parts by reacting halogen-terminated MXenes with deprotonated organic amines. The resulting hybrid structures unite tailorability of organic molecules with electronic connectivity and other properties of inorganic 2D materials. Describing the structure of h-MXene necessitates the integration of concepts from coordination chemistry, self-assembled monolayers and surface science. The optical properties of h-MXenes reveal coherent coupling between the organic and inorganic constituents. h-MXenes also exhibit superior stability against hydrolysis.

Covalent surface modifications and superconductivity of two-dimensional metal carbide MXenes.

Versatile chemical transformations of surface functional groups in two-dimensional transition-metal carbides (MXenes) open up a previously unexplored design space for this broad class of functional materials. We introduce a general strategy to install and remove surface groups by performing substitution and elimination reactions in molten inorganic salts. Successful synthesis of MXenes with oxygen, imido, sulfur, chlorine, selenium, bromine, and tellurium surface terminations, as well as bare MXenes (no surface termination), was demonstrated. These MXenes show distinctive structural and electronic properties. For example, the surface groups control interatomic distances in the MXene lattice, and Ti n +1C n (n = 1, 2) MXenes terminated with telluride (Te2-) ligands show a giant (>18%) in-plane lattice expansion compared with the unstrained titanium carbide lattice. The surface groups also control superconductivity of niobium carbide MXenes.

Quasi-Binary Transition Metal Dichalcogenide Alloys: Thermodynamic Stability Prediction, Scalable Synthesis, and Application.

Transition metal dichalcogenide (TMDCs) alloys could have a wide range of physical and chemical properties, ranging from charge density waves to superconductivity and electrochemical activities. While many exciting behaviors of unary TMDCs have been demonstrated, the vast compositional space of TMDC alloys has remained largely unexplored due to the lack of understanding regarding their stability when accommodating different cations or chalcogens in a single-phase. Here, a theory-guided synthesis approach is reported to achieve unexplored quasi-binary TMDC alloys through computationally predicted stability maps. Equilibrium temperature-composition phase diagrams using first-principles calculations are generated to identify the stability of 25 quasi-binary TMDC alloys, including some involving non-isovalent cations and are verified experimentally through the synthesis of a subset of 12 predicted alloys using a scalable chemical vapor transport method. It is demonstrated that the synthesized alloys can be exfoliated into 2D structures, and some of them exhibit: i) outstanding thermal stability tested up to 1230 K, ii) exceptionally high electrochemical activity for the CO2 reduction reaction in a kinetically limited regime with near zero overpotential for CO formation, iii) excellent energy efficiency in a high rate Li-air battery, and iv) high break-down current density for interconnect applications. This framework can be extended to accelerate the discovery of other TMDC alloys for various applications.

Prevalencia de los defectos de desarrollo del esmalte de la especialidad de odontologia infantil en la UJAT 2021-2022 / Prevalência de defeitos de desenvolvimento do esmalte da especialidade de odontologia infantil da UJAT 2021-2022 / Prevalence of enamel development defects of the specialty of children's dentistry at the UJAT 2021-2022

Objetivo: Conocer la prevalencia de los Defectos del desarrollo del esmalte en pacientes de la especialidad de odontología infantil en la UJAT. Material y Método: Se realizó un estudio observacional, transversal, prospectivo, cuantitativo, que permitirá conocer la frecuencia y prevalencia de los defectos del esmalte en pacientes infantiles de la especialidad de odontología infantil de la UJAT. La población de estudio fue finita a conveniencia del investigador ya que se conoce el número de pacientes que integran el estudio. La investigación se llevó a cabo con un universo de 300 pacientes con una población analizada de entre 0 a 15 años de la cual se obtuvo una muestra de 195 pacientes durante el periodo 2021-2022, con un intervalo de confianza del 95% y un margen de error del 5%. Variables: edad, género, arcada con mayor afectación, cantidad de órganos dentales y tipo de dentición. Resultados: El defecto del esmalte más prevalente resultó ser Hipoplasia seguido del HIM, con afectación principalmente del sexo femenino y en la edad de 4 a 8 años, se observó que ambas arcadas son afectadas, que la dentición mixta es la más afectada, los órganos dentales más afectados fueron los incisivos centrales y los 1ros molares, en relación con los antecedentes perinatales no se presentó alguna complicación como mayor afectación. Conclusiones: El principal defecto de la estructura del esmalte es la Hipoplasia y la presentan más las mujeres y el rango de edad donde se observó la mayor prevalencia es de 4 a 8 años

Objetivo: Conhecer a prevalência de defeitos de desenvolvimento do esmalte em pacientes especializados em odontologia infantil na UJAT. Material e Método: Foi realizado um estudo observacional, transversal, prospectivo, quantitativo, que permitirá conhecer a frequência e prevalência de defeitos de esmalte em pacientes crianças da especialidade de odontologia infantil da UJAT. A população do estudo foi finita para a conveniência do investigador, uma vez que o número de pacientes no estudo é conhecido. A pesquisa foi realizada com um universo de 300 pacientes com população analisada entre 0 e 15 anos de idade, dos quais foi obtida uma amostra de 195 pacientes no período de 2021 a 2022, com intervalo de confiança de 95% e margem de erro de 5%. Variávis: idade, sexo, arco com maior envolvimiento, número de órgaõs dentários e tipo de dentição. Resultados: O defeito do esmalte mais prevalente foi a Hipoplasia seguida pela HIC, com acometimento principalmente feminino e na idade de 4 a 8 anos, observou-se que ambos os arcos são acometidos, que a dentição mista é a mais acometida, os órgãos dentários mais afetados foram os incisivos centrais e os 1º molares, Em relação à história perinatal, não houve complicação como maior envolvimento. Conclusões: O principal defeito da estrutura do esmalte é a hipoplasia e é mais apresentado pelas mulheres e a faixa etária onde a maior prevalência foi observada é de 4 a 8 anos

Objective: To determine the prevalence of enamel defects in patients of the Specialty in Pediatric Dentistry in the UJAT. Material and Method: An observational, cross-sectional, prospective, quantitative study was carried out, which allowed to know the frequency and prevalence of enamel defects in child patients of the Specialty in Pediatric Dentistry at the UJAT. The study population was finite at the convenience of the researcher since the number of patients that make up the study is know. The research was carried out with a universe of 300 patients with a population analyzed population between 0 and 15 years of age from which a sample of 195 patients was obtained during the period 2021-2022, with a confidence interval of 95% and a margin of error of 5%. Variables: age, gender, arch with greater involvement, number of dental organs and type of dentition. Results: The most prevalent enamel defect turned out to be Hypoplasia followed by MIH, affecting mainly females and between the ages of 4 and 8 years, it was observed that both arches are affected, that the mixed dentition is the most affected, the most affected teeth stated were the central incisors and the first molars; In most cases, the perinatal history stated there was no complication as greater involvement. Conclusions: The main defect if enamel structure is Hypoplasia and it is presented more bye the women and the age range where the highest prevalence was observed is from 4 to 8 years

Influencia del uso de injertos óseos asociados a corticotomía. Revisión Sistemática

Introducción: La corticotomía corresponde a un procedimiento quirúrgico, basado en el Fenómeno de Aceleración Regional (RAP), que tiene por objetivo disminuir hasta en un tercio el tiempo del tratamiento ortodóncico. Esta técnica se puede ejecutar agregando un injerto óseo que aumenta el grosor alveolar, lo que se conoce como Ortodoncia Osteogénica Acelerada Periodontalmente (PAOO) permitiendo un movimiento más amplio y rápido. Objetivo: Determinar la condición final del tejido óseo vestibular en pacientes tratados con corticotomía que recibieron injerto óseo versus pacientes que no recibieron. Materiales y métodos: Se realiza una búsqueda electrónica en la Biblioteca Nacional de Medicina PUBMED bajo la estrategia: "orthodontics" OR "orthodontic treatment" and "osteotomy" OR "corticotomy" OR "periodontally accelerated" and "bone graft" OR "bone grafting" OR "augmented corticotomy" AND "tooth movement". Se realizó el análisis de riesgo de sesgo con la herramienta ROBINS-I. Resultados: La búsqueda arrojo un total de 92 artículos de los cuales 4 fueron elegidos para el análisis Conclusión: Existe una cantidad limitada de estudios sobre el tema, presentando riesgo de sesgo de moderado a alto. Considerando esto, la evidencia indica que la utilización de injerto óseo y membrana contribuye a mejorar las condiciones anatómicas, especialmente si esta última se utiliza fijada.

Introduction: Corticotomy is a surgical procedure based on the Regional Acceleratory Phenomenon (RAP), whose objective is to reduce up to a third the time of orthodontic treatment. This technique can be performed adding a bone graft for the augmentation of the alveolar width and allowing a broader movement. This is known as Periodontally accelerated osteogenic orthodontics (PAOO). Objective: To determine the final condition of the buccal bone tissue after treatment in patients who received corticotomy and bone graft versus corticotomy alone. Materials and methods: An electronic search in the National Library of Medicine PUBMED was performed utilizing the following strategy: "orthodontics" OR "orthodontic treatment" and "osteotomy" OR "corticotomy" OR "periodontally accelerated" and "bone graft" OR "bone grafting" OR "augmented corticotomy" AND "tooth movement". Risk of bias analysis was done utilizing the ROBINS-I tool. Results: The search yielded a total of 92 articles, of which 4 were considered for analysis. Conclusion: There is a limited number of studies regarding this topic and their risk of bias is moderate to high. Thus, the available evidence suggests that the use of bone graft and a resorbable membrane contributes to the improvement of the anatomical conditions, especially if the latter is fixed.