Thermal, viscoelastic, and electrical properties of thermoplastic polyurethane films reinforced with multi-walled carbon nanotubes.

Thermoplastic polyurethane (TPU) doped with multi-walled carbon nanotubes (MWCNTs) at 1, 3, 5, and 7 wt% has been studied. The effect of MWCNTs on thermal, viscoelastic, and electric properties in the TPU matrix was characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and by impedance spectroscopy. The results show that the thermal, electrical, and viscoelastic properties, such as the glass transition temperature, shifted towards high temperatures. The melting temperature decreased, and the conductivity and the storage modulus increased by 61.5 % and 58.3 %. The previously observed behavior on the films is due to the increase in the mass percentage of carbon nanotubes (CNTs) in the TPU matrix. Also, it can be said that the CNTs were homogeneously dispersed in the TPU matrix, preventing the movement of the polymer chains, and generating channels or connections that increase the conductivity and improve the thermal properties of the material.

Evidence of a Proximity Effect in a (AgI)x - C(1-x) Mixture Using a Simulation Model Based on Random Variable Theory.

Silver iodide is a prototype compound of superionic conductors that allows ions to flow through its structure. It exhibits a first-order phase transition at 420 K, characterized by an abrupt change in its ionic conductivity behavior, and above this temperature, its ionic conductivity increases by more than three orders of magnitude. Introducing small concentrations of carbon into the silver iodide structure produces a new material with a mixed conductivity (ionic and electronic) that increases with increasing temperature. In this work, we report the experimental results of the ionic conductivity as a function of the reciprocal temperature for the (AgI)x - C(1-x) mixture at low carbon concentrations (x = 0.99, 0.98, and 0.97). The ionic conductivity behavior as a function of reciprocal temperature was well fitted using a phenomenological model based on a random variable theory with a probability distribution function for the carriers. The experimental data show a proximity effect between the C and AgI phases. As a consequence of this proximity behavior, carbon concentration or temperature can control the conductivity of the (AgI)x - C(1-x) mixture.

Nanoparticles of the Perovskite-Structure CaTiO3 System: The Synthesis, Characterization, and Evaluation of Its Photocatalytic Capacity to Degrade Emerging Pollutants.

In this research work, the photocatalytic capacity shown by the nanoparticles of the CaTiO3 system was evaluated to degrade two pollutants of emerging concern, namely methyl orange (MO)-considered an organic contaminating substance of the textile industry that is non-biodegradable when dissolved in water-and levofloxacin (LVF), an antibiotic widely used in the treatment of infectious diseases that is released mostly to the environment in its original chemical form. The synthesis process used to obtain these powders was the polymeric precursor method (Pechini), at a temperature of 700 °C for 6 h. The characterization of the obtained oxide nanoparticles of interest revealed the presence of a majority perovskite-type phase with an orthorhombic Pbnm structure and a minority rutile-type TiO2 phase, with a P42/mnm structure and a primary particle size <100nm. The adsorption-desorption isotherms of the synthesized solids had H3-type hysteresis loops, characteristic of mesoporous solids, with a BET surface area of 10.01m2/g. The Raman and FTIR spectroscopy results made it possible to identify the characteristic vibrations of the synthesized system and the characteristic deformations of the perovskite structure, reiterating the results obtained from the XRD analysis. Furthermore, a bandgap energy of ~3.4eV and characteristic emissions in the violet (437 nm/2.8 eV) and orange (611 nm/2.03 eV) were determined for excitation lengths of 250 nm and 325 nm, respectively, showing that these systems have a strong emission in the visible light region and allowing their use in photocatalytic activity to be potentialized. The powders obtained were studied for their photocatalytic capacity to degrade methyl orange (MO) and levofloxacin (LVF), dissolved in water. To quantify the coloring concentration, UV-visible spectroscopy was used considering the variation in the intensity of the characteristic of the greatest absorption, which correlated with the change in the concentration of the contaminant in the solution. The results showed that after irradiation with ultraviolet light, the degradation of the contaminants MO and LVF was 79.4% and 98.1% with concentrations of 5 g/L and 10 g/L, respectively.

Performance of a pilot-scale BDD reactor by numerical analysis of reaction rate parameters and additional numbers for mass transfers.

The performance of a pilot-scale boron-doped diamond (BDD) reactor through a numerical analysis of reaction rate parameters and enhanced mass transfer has been investigated. The main objective of this research is to evaluate the efficiency of the reactor in mineralizing and degrading caffeine as an emerging contaminant. Based on the kinetic mechanisms and mass transport correlations reported in the literature, two reaction rate kinetic models for caffeine degradation are proposed and analyzed. The models consider different electrolytes (NaCl and Na2SO4) and applied current densities. The kinetic fitting process utilizes the gradient-maximal electrochemical approach, together with orthogonal placement methods, fourth-order Runge-Kutta (RK4) methods, and Nelder & Mead methods for optimization of kinetic parameters and spatial discretization of the material balance. Experimental data obtained from a factorial design with four factors and two levels (24) validate the proposed kinetic models. Caffeine degradation is achieved with NaCl and Na2SO4 electrolytes at concentrations of 60 ppm and 100 ppm, respectively. The corresponding applied loads are 1.5 AhL-1 and 3 AhL-1. Na2SO4 exhibits superior performance with a total organic carbon (TOC) removal efficiency of 99.13%, while NaCl achieves 31.47% mineralization. The behavior of caffeine degradation under the operational and scale conditions demonstrates that NaCl, as a support electrolyte, enables controlled charge transfer (current density) during the degradation process. In contrast, Na2SO4 as a support electrolyte introduces a mixed control of charge and mass transfer. The pilot-scale kinetic parameters obtained in this study provide valuable insights into the support electrolyte dynamics and current density dynamics in BDD-based Electrooxidation (EO) systems, particularly in complex matrix applications. Furthermore, the observed electrical consumption supports the potential application of EO as a viable technology for industrial-scale tertiary wastewater treatment, specifically for caffeine removal.

Morphological Electrical and Hardness Characterization of Carbon Nanotube-Reinforced Thermoplastic Polyurethane (TPU) Nanocomposite Plates.

The impacts on the morphological, electrical and hardness properties of thermoplastic polyurethane (TPU) plates using multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers have been investigated, using MWCNT loadings between 1 and 7 wt%. Plates of the TPU/MWCNT nanocomposites were fabricated by compression molding from extruded pellets. An X-ray diffraction analysis showed that the incorporation of MWCNTs into the TPU polymer matrix increases the ordered range of the soft and hard segments. SEM images revealed that the fabrication route used here helped to obtain TPU/MWCNT nanocomposites with a uniform dispersion of the nanotubes inside the TPU matrix and promoted the creation of a conductive network that favors the electronic conduction of the composite. The potential of the impedance spectroscopy technique has been used to determine that the TPU/MWCNT plates exhibited two conduction mechanisms, percolation and tunneling conduction of electrons, and their conductivity values increase as the MWCNT loading increases. Finally, although the fabrication route induced a hardness reduction with respect to the pure TPU, the addition of MWCNT increased the Shore A hardness behavior of the TPU plates.

Study of the Properties of CdS:Al (R = [Al3+]/[Cd2+] = 0.30, 0.40, 0.50) Thin Films Grown by the CBD Method in an Ammonia-Free System.

CdS:Al thin films were fabricated on a glass substrate using the CBD method. The effect of aluminum incorporation on the structural, morphological, vibrational, and optical properties of CdS thin layers was investigated by X-ray diffraction (XRD), Raman spectroscopy (RS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and UV-visible (UV-vis) and photoluminescence (PL) spectroscopies. XRD analysis of deposited thin films confirmed a hexagonal structure with a preferred (002) orientation in all samples. The crystallite size and surface morphology of the films are modified with aluminum content. Raman spectra exhibit fundamental longitudinal optical (LO) vibrational modes and their overtones. Optical properties were studied for each thin film. Here, it was observed that the optical properties of thin films are affected by the incorporation of aluminum into the CdS structure.

Interactions of Sodium Salicylate with ß-Cyclodextrin and an Anionic Resorcin[4]arene: Mutual Diffusion Coefficients and Computational Study.

The interaction between sodium salicylate (NaSal) and the two macrocycles 5,11,17,23-tetrakissulfonatomethylene-2,8,14,20-tetra(ethyl)resorcinarene (Na4EtRA) and ß-cyclodextrin (ß-CD) has been studied by the determination of ternary mutual diffusion coefficients, and spectroscopic and computational techniques. The results obtained by the Job method suggest that the complex formation is given in a 1:1 ratio for all systems. The mutual diffusion coefficients and the computational experiments have shown that the ß-CD-NaSal system presents an inclusion process, whereas the Na4EtRA-NaSal system forms an outer-side complex. This fact is also in line with the results obtained from the computational experiments, where the calculated solvation free energy has been found to be more negative for the Na4EtRA-NaSal complex because of the partial entry of the drug inside the Na4EtRA cavity.

Frecuencia del dolor anterior de rodilla luego de reconstrucción del ligamento cruzado anterior con autoinjerto hueso-tendón-hueso / Frequency of anterior knee pain following anterior cruciate ligament reconstruction with bone-tendon-bone autograft

Introducción. La ruptura del ligamento anterior cruzado (LCA) es una condición frecuente a nivel global y la reconstrucción artroscópica con autoinjerto de hueso-tendón-hueso (HTH) constituye una de las técnicas quirúrgicas para su tratamiento. No obstante, esta técnica puede generar complicaciones como dolor anterior de rodilla. Actualmente, se desconoce su prevalencia en Colombia.Objetivo. Determinar la frecuencia de dolor anterior de rodilla luego de la reconstrucción de LCA con autoinjerto HTH en pacientes operados en un periodo de 4 años en el Hospital San José en Bogotá, Colombia.Metodología. Estudio descriptivo realizado en pacientes con diagnóstico de ruptura del LCA llevados a cirugía de reconstrucción de este ligamento mediante HTH entre enero de 2014 y diciembre de 2017. Se realizó una encuesta telefónica y, en los pacientes con dolor, una valoración clínica para caracterizar dicho dolor. Los datos se describen usando frecuencias absolutas y relativas, así como medianas y rangos.Resultados. Se incluyeron 257 pacientes, la mayoría de los cuales eran hombres (87,5%) y adultos jóvenes (42,4%). La prevalencia del dolor anterior de rodilla fue 11,6%. Además, ninguno de los pacientes operados en 2014 presentó dolor anterior de rodilla en el momento de la valoración (a 4 o más años de seguimiento).Conclusiones. La reconstrucción del LCA mediante HTH es una técnica quirúrgica que ofrece excelentes resultados en términos de escalas funcionales y estabilidad de la rodilla. La prevalencia de dolor anterior de rodilla fue inferior a la reportada en otros estudios y se localizó con mayor frecuencia en el sitio donante (polo inferior de la rótula y tuberosidad tibial anterior)

Introduction. Anterior cruciate ligament (ACL) injury is a common condition worldwide, and one of the surgical techniques used to treat it is arthroscopic reconstruction with bone-tendon-bone (BTB) autograft. However, this technique can result in complications such as anterior knee pain, but its prevalence in Colombia is currently unknown.Objective. To establish the frequency of anterior knee pain after ACL reconstruction using BTB autograft in patients operated on over a 4-year period at the Hospital San José in Bogotá, Colombia.Methodology. Descriptive study performed in patients diagnosed with ACL injury and taken to ACL reconstruction surgery using BTB autograft between January 2014 and December 2017. A telephone survey and a clinical assessment were performed to characterize pain in patients presenting with this symptom. Data are described using absolute and relative frequencies, as well as medians and ranges.Results. A total of 257 patients were included, most of whom were male (87.5%) and young adults (42.4%). The prevalence of anterior knee pain was 11.6%. Moreover, none of the patients operated on in 2014 had anterior knee pain at the time of assessment (at 4 or more years of follow-up).Conclusions. ACL reconstruction using BTB autograft is a surgical technique that offers outstanding outcomes in terms of functional scales and knee stability. The frequency of anterior knee pain was lower than reported in other studies and was more frequently located at the donor site (lower pole of the patella and anterior tibial tuberosity)

Fundación Universitaria de Ciencias de la Salud: visión 2023 / The Health Sciences University Foundation's visión for 2023

La FUCS, siguiendo la visión y la filosofía de los Fundadores de la Sociedad de Cirugía de Bogotá-Hospital de San José, ha estructurado su futuro y ese ordenamiento especíco constituye una de las razones para explicar su crecimiento. A través de la historia, la educación ha sido uno de los pilares sustantivos para salir del subdesarrollo, por lo que eles a nuestra tradición y a lo enunciado en la visión, el objetivo es que en el año 2030 seamos reconocidos nacional e internacionalmente como una institución del más alto prestigio en la formación de estudiantes, con la seguridad de que impactaremos en forma positiva en el desarrollo de nuestro país.

The FUCS, following the vision and philosophy of the Founders of the Society of Surgery of Bogotá-Hospital de San José, has structured its future and this specific organization constitutes one of the reasons to explain its growth. Throughout history, education has been one of the substantive pillars to overcome underdevelopment, so faithful to our tradition and what is stated in the vision, the objective is that in the year 2030 we will be recognized nationally and internationally as an institution of the highest prestige in the training of students, with the assurance that we will have a positive impact on the development of our country.

Surface and Electrical Characterization of Bilayers Based on BiFeO3 and VO2.

Thin films of BiFeO3, VO2, and BiFeO3/VO2 were grown on SrTiO3(100) and Al2O3(0001) monocrystalline substrates using radio frequency and direct current sputtering techniques. To observe the effect of the coupling between these materials, the surface of the films was characterized by profilometry, atomic force microscopy, and X-ray photoelectron spectroscopy. The heterostructures, monolayers, and bilayers based on BiFeO3 and VO2 grew with good adhesion and without delamination or signs of incompatibility between the layers. A good granular arrangement and RMS roughness between 1 and 5 nm for the individual layers (VO2 and BiFeO3) and between 6 and 18 nm for the bilayers (BiFeO3/VO2) were observed. Their grain size is between 20 nm and 26 nm for the individual layers and between 63 nm and 67 nm for the bilayers. X-ray photoelectron spectroscopy measurements show a higher proportion of V4+, Bi3+, and Fe3+ in the films obtained. The homogeneous ordering, low roughness, and oxidation states on the obtained surface show a good coupling in these films. The I-V curves show ohmic behavior at room temperature and change with increasing temperature. The effect of coupling these materials in a thin film shows the appearance of hysteresis cycles, I-V and R-T, which is typical of materials with high potential in applications, such as resistive memories and solar cells.

Recognition of Heavy Metals by Using Resorcin[4]arenes Soluble in Water.

The complexing properties of two water-soluble resorcin[4]arenes (tetrasodium 5,11,17,23-tetrakissulfonatemethylen 2,8,14,20-tetra(butyl)resorcin[4]arene, Na4BRA, and tetrasodium 5,11,17,23-tetrakissulfonatemethylen-2,8,14,20-tetra(2-(methylthio)ethyl)resorcin[4]arene, Na4SRA) with polluting heavy metals such as Cu2+, Pb2+, Cd2+ and Hg2+ were studied by conductivity, and the findings were confirmed by using other techniques to try to apply this knowledge to removing them. The results indicate that Na4BRA is able to complex Cu2+ in a 1:1 ratio and Pb2+ in a 1:2 ratio, while Na4SRA complexes Hg2+ in a 1:1 ratio. On the contrary, no indications have been observed that either of the resorcin[4]arenes studied complexes the Cd2+ ions. The results suggest that the bonds established between the sulfur atoms located at the lower edge of the SRA4- and the solvent hydrogens could prevent the entry of the guest into the host cavity. However, in the case of Hg2+ ions, the entry is favoured by the interactions between the sulfur donor atoms present on the lower edge of Na4SRA and the Hg2+ ions. Therefore, it can be said that Na4BRA is selective for Cu2+ and Pb2+ ions and Na4SRA is selective for Hg2+ ions.

Plastic recycling and their use as raw material for the synthesis of carbonaceous materials.

Pollution by polymeric materials - in particular plastics - has a negative effect on the health of our planet. Approximately 4.9 billion tons of plastic are estimated to have been improperly disposed of, with the environment as their final destination. This scenario comes from a linear economic system, extraction-production-consumption and finally disposal. The alarming panorama has created the need to find technological solutions that generate new uses for discarded polymeric materials or turn them into part of the production process to produce new and novel materials, such as carbon nanotubes, graphene, or other carbonaceous materials of high added value, modifying the economy for a circular and sustainable production model. This review highlights the negative impact that the disposal of plastic materials has on the environment and the research needs that allow solving the pollution problems generated in the environment by these wastes. Also, the review highlights the current and future directions of recovery plastic waste research-based to promote innovations in the plastic production sector that could allow obtaining breakpoints in other industrial sectors with the technology-based companies.

Ionic effects on supramolecular hosts: solvation and counter-ion binding in polar media.

For the progress of synthetic supramolecular chemistry in aqueous solution the design of host molecules soluble in this medium is essential. A possible route is the introduction of ionic residues, with the additional advantage that also electrostatic interactions can be used to form supramolecular architectures. In this work we study the effect of different ionic substituents on a resorcin[4]arene host on solvation and counterion binding in water and dimethyl sulfoxide (DMSO). To do so, we combine dielectric relaxation spectroscopy (DRS) at 298.15 K and dilute-solution conductivity measurements covering 278.15-308.15 K. The results indicate that studied substituents lead to a comparable increase in solubility in both water and the dipolar-aprotic DMSO. However, solvation and counterion binding not only depend on the nature of the ionic substituent but also on the solvent. Although intrinsically hydrophobic in nature, resorcin[4]arenes with ionic substituents also show strong hydrophilic hydration in water, with the extent depending on the nature of the ionic group. In contrast to that, solvophobicity apparently dominates the interactions of DMSO with the solute. Counterion binding was found for both solvents and is essentially determined by solvent polarity. It appears that, compared to neat DMSO, the solubility of the cationic resorcin[4]arene with dimethylamine substituents is strongly increased in water-DMSO mixtures due to the formation of hydrogen bonds between two DMSO molecules and one water molecule.

Raman analysis of intermediate phases during melting and freezing in long-chain n-alkanes.

Structural changes of the n-alkanes (n = 18, 20, 21, 22) have been investigated by Raman spectroscopy during the melting from solid phase to the intermediate transition phase to the molten phase. With increasing temperature docosane (C22) undergoes an orthorhombic-hexagonal (rotator, R) phase follow by an alpha (α) phase. In addition, the α phase as an intermediate transition between the solid and liquid phases is observed in heneicosane (C21). For eicosane (C20) and octadecane (C18) the transition from solid to liquid phase is almost instantaneous unlike docosane (C22) and heneicosane (C21) where the intermediate transitions are observed. During freezing from the liquid phase, the even n-alkanes show the rotator phase (R) a few degrees lower than melting and just before the crystalline solid phase. The intermediate phase transition temperature can be spectrally determined with the 1100-1350 cm-1 Raman region of the CH2 band.

Low-Density Granulocytes and Neutrophil Extracellular Traps as Biomarkers of Disease Activity in Adult Inflammatory Myopathies.

BACKGROUND/OBJECTIVE: Biomarkers for disease activity and damage accrual in idiopathic inflammatory myopathies (IIMs) are currently lacking. The purpose of this cross-sectional study is to analyze the relationship among low-density granulocytes (LDGs), neutrophil extracellular traps (NETs), and clinical and immunological features of patients with IIM. METHODS: We assessed disease activity, damage accrual, amount of LDGs, NETs, expression of LL-37, and serum cytokines in 65 adult patients with IIM. Differences between groups and correlations were assessed by Kruskal-Wallis, Mann-Whitney U, and Spearman ρ tests. The association between LDGs, NETs, disease activity, calcinosis, and cutaneous ulcers was assessed by logistic regression. To address the capacity of LDGs and NETs to diagnose disease activity, we used receiving operating characteristic curves. RESULTS: Low-density granulocytes were higher in patients with active disease, ulcers, calcinosis, and anti-MDA5 antibodies, which correlated with serum levels of IL-17A and IL-18. Neutrophil extracellular traps were higher in patients with calcinosis, elevated titers of antinuclear antibodies, and positive anti-PM/Scl75 tests. The combination of a high proportion of both total LDGs and NETs was associated with the presence of calcinosis and cutaneous ulcers. LL-37 was higher in NETs originating from LDGs. Normal-density neutrophils were elevated in patients with active dermatomyositis. CONCLUSIONS: Low-density granulocytes and NETs containing LL-37 are increased in patients with IIM and active disease, and correlate with proinflammatory cytokines. Both total and CD10+ LDGs are potential biomarkers for disease activity and, in combination with NETs, have the potential to detect patients who are at risk for cutaneous ulcers and calcinosis.

Hydrogen storage in purified multi-walled carbon nanotubes: gas hydrogenation cycles effect on the adsorption kinetics and their performance.

Multi-walled carbon nanotubes (MWCNTs) are an alternative for storage with low cost, eco-friendly, and good performance for both process adsorption and desorption. Herein, a purification procedure of MWCNTs was successfully described and studied by using XRD, TEM, Raman spectroscopy and by means of N2 adsorption-desorption isotherms using the BET method. The H2 storage properties at room temperature of the purified carbon nanotubes exposed to gas under pressures between 0.39 and 13.33 kPa was investigated by using the quartz crystal microbalance technique. It was found that the H2 adsorption capacity is strongly dependent on the morphological and structural characteristics of the carbon nanotubes and their specific surface area. The best sample with specific surface area of 729.4 ± 3 m2 g-1 shows a maximum adsorption capacity of 3.46 wt% at 12.79 kPa of H2 exposure pressure. The adsorption kinetics (t95%) from the different purified MWCNTs was also investigated as a function of the H2 exposure pressure as well as the performance of these MWCNTs on the reversibility of the H2 loading/unloading process when underwent to successive cycles of gas exposure.

Medición del Ángulo de Inclinación del Ligamento Cruzado Anterior (LCA). Serie de Casos / Anterior Cruciate Ligament (ACL) Inclination angle measurement. Case Series

Introducción La evaluación de la inclinación del ligamento cruzado anterior(LCA) es útil tanto en pacientes que no han sido llevados a procedimientos reconstructivos para aclarar dudas diagnósticas ante la sospecha de una lesión parcial como para el planeamiento quirúrgico; y en el postoperatorio para evaluar la calidad y efectividad al restaurar las inserciones anatómicas del ligamento. Sin embargo en nuestro medio no existe un referente local de medición ni un entrenamiento en la toma de la misma. Objetivo Medir el ángulo de inclinación del LCA en rodillas sanas de nuestra población, utilizando técnicas de medición por resonancia magnética (RM) entre junio del 2013 y junio del 2017. Métodos Estudio descriptivo tipo serie de casos, se incluyeron los pacientes sometidos a RM en el servicio de radiología de nuestro hospital que fueron leídas como normales. Las mediciones del ángulo de inclinación se tomaron en los planos sagital, coronal y axial. Resultados Se incluyeron 91 pacientes (45% (n=41) Hombres / 55% (n=50) Mujeres). Se encontró un ángulo de inclinación del LCA en el plano sagital con una media de 45.31 (DE: 5.39), en el plano coronal de 70.68 (DE:5.79) y 68.49 (DE:5.61) en el plano axial, sin encontrarse diferencias imagenológicas segmentados por sexo, edad o lateralidad. Discusión No se aprecian diferencias en las imágenes de RM en el ángulo de inclinación en ninguno de los tres planos entre hombres y mujeres, tampoco respecto a lateralidad o grupos de edad. Se obtuvieron resultados que aún no están descritos en la literatura; los obtenidos son similares a los reportados en la literatura

Background The evaluation of the inclination of the anterior cruciate ligament (ACL) is useful to clarify diagnostic doubts in patients who have not been taken to reconstructive procedures and to evaluate the quality and effectiveness of restoring the anatomical attachments of the ligament. after an ACL surgery reconstruction. However, in our environment there is no local measurement reference or training in measuring it inclination angle. The aim of the study is to measure the inclination angle of the ACL in healthy knees of our population, using magnetic resonance (MRI) measurement techniques. Methods A Case Series study was performed, including patients who underwent to knee MRI between June 2013 and June 2017 that were read as normal. Inclination angle measurements of the ACL were taken in the sagittal, coronal, and axial planes. Results 91 patients were included (45% (n=41) Men / 55% (n=50) Women). An ACL inclination angle was found in the sagittal plane with a mean of 45.31 (SD: 5.39), in the coronal plane of 70.68 (SD: 5.79) and 68.49 (SD: 5.61) in the axial plane, with no imaging differences found. segmented by sex, age or laterality. Discussion There are no differences in the MRI images in the angle of inclination in any of the three planes between men and women, neither with regard to laterality or age groups. Results were obtained that have not yet been described in the literature; those obtained are similar to those reported in the literature

¿Es útil fijar las fracturas de Segond para el manejo de la inestabilidad anterolateral de rodilla? A propósito de un caso / Is it worthwhile fixing Segond fractures for the management of anterolateral knee instability? A case report

Introducción El complejo anterolateral de la rodilla es un estabilizador secundario de la rotación tibial interna, su inserción distal esta localizada en el aspecto anterolateral de la tibia proximal y su avulsión es conocida como fractura de Segond, fue descrita hace mas de un siglo por el cirujano francés que le dio su nombre. Es frecuente la asociación de la lesión del ligamento cruzado anterior (LCA) con este complejo, tanto que en la actualidad se considera la fractura de Segond como un signo patognomónico de ruptura del cruzado anterior. Dada la importancia de brindar estabilidad rotacional desde la periferia de la articulación y las propiedades cada vez mas reconocidas de las estructuras anterolaterales, este artículo reporta un caso de fijación directa de la fractura de Segond, en el cual se buscó restituir la anatomía original de la rodilla. Métodos Revisión de la literatura relevante y reporte retrospectivo del caso de un paciente con lesión de LCA y fractura de Segond que fue llevado a reconstrucción de LCA con autoinjerto de HTH y reducción directa y fijación con sutura de anclaje de fractura de Segond por una incisión mínima, con un seguimiento clínico de 4 años. Se aplicaron escalas de valoración subjetiva previo al procedimiento y en el seguimiento postoperatorio. Resultados La inestabilidad anterior y anterolateral posterior al manejo quirúrgico presentó mejoría clínica pasando de tener Lachman IIB a negativo, y Pivot shift grado II a negativo. Las escalas de valoración subjetivas de Lysholm e IKDC mejoraron notablemente de resultados regulares previo al procedimiento a excelentes en el postoperatorio. No presentó complicaciones durante el procedimiento ni requirió reintervenciones. Discusión Aunque la fractura de Segond está descrita desde hace más de un siglo, y su asociación con lesiones de ligamento cruzado anterior se documentó hace mas de 20 años, aun no hay consenso en el manejo de esta fractura. Desde el punto de vista biomecánico, una estructura localizada en el centro de la rodilla como el LCA, de manera aislada, sería insuficiente para controlar la rotación tibial en relación al fémur. Por lo tanto, sería lógico pensar que una estructura localizada lejos del centro de rotación de la rodilla pueda ser más efectiva en controlar la rotación ya que ejerce un mayor control del torque rotacional. Reportamos resultados funcionales satisfactorios y estabilidad postoperatoria adecuada a 4 años de seguimiento, posterior a la fijación de la fractura de Segond asociada a reconstrucción de LCA; consideramos que puede ser una medida exitosa y segura para el manejo de la inestabilidad anterolateral de la rodilla.

Introduction The anterolateral complex of the knee is a secondary stabiliser of the internal tibial rotation. Its distal insertion is located in the anterolateral aspect of the proximal tibia, and its avulsion is known as Segond fracture. This was described more than a century ago by the French surgeon who gave it his name. The combination of anterior cruciate ligament injury (ACL) with the anterolateral complex is so common in as much that Segond fracture is currently considered as a pathognomonic sign of rupture of the anterior cruciate. Given the importance of providing rotational stability from the periphery of the joint and the increasingly recognised properties of the anterolateral structures, this article reports a case of direct fixation of the Segond fracture, in which it was sought to restore the original anatomy of the knee. Methods Review of relevant literature and retrospective case report of a patient with ACL injury and Segond fracture who underwent ACL reconstruction with a host-to-host (HTH) autograft and direct reduction and fixation with Segond fracture anchor suture through a minimal incision. There was a clinical follow-up of 4 years. Subjective assessment scales were applied prior to the procedure and in the postoperative follow-up. Results Anterior and anterolateral instability after surgical management showed a clinical improvement, going from having Lachman IIB to negative, and from Pivot shift grade II to negative. The subjective rating scales of Lysholm and International Knee Documentation Committee (IKDC) improved markedly from regular results prior to the procedure to excellent in the postoperative period. There were no complications during the procedure and no reoperations were required Discussion Although the Segond fracture has been described for more than a century, and its association with anterior cruciate ligament injuries was documented more than 20 years ago, there is still no consensus on the management of this fracture. From the biomechanical point of view, a structure located in the centre of the knee like the ACL, in isolation, would be insufficient to control the tibial rotation in relation to the femur. Therefore, it would be logical to think that a structure located far from the centre of rotation of the knee can be more effective in controlling rotation, since it exerts a greater control of rotational torque. Satisfactory functional results are reported, together with an adequate postoperative stability at 4 years of follow-up, after the fixation of the Segond fracture associated with ACL reconstruction. It is considered that this can be a successful and safe measure for the management of anterolateral instability of the knee.

Insights into the behavior of six rationally designed peptides based on Escherichia coli's OmpA at the water-dodecane interface.

The Escherichia coli's membrane protein OmpA has been identified as a potential biosurfactant due to their amphiphilic nature, and their capacity to stabilize emulsions of dodecane in water. In this study, the influence of surfactant type, concentration, preservation time and droplet size on the crystallization of n-dodecane and water, in oil-in-water emulsions stabilized with six rationally designed Escherichia coli's OmpA-based peptides was investigated. A differential scanning calorimetry (DSC) protocol was established using emulsions stabilized with Tween 20® and Tween 80®. A relationship between the surfactant concentration and the crystallization temperatures of n-dodecane and water was observed, where the crystallization temperatures seem to be dependent on the preservation time. A deconvolution analysis shows that the peak morphology possibly depends on the interactions at the interface because the enthalpic contributions of each Gaussian peak remained similar in emulsions stabilized with the same peptide. Adsorption results show that the main driver for adsorption and thus stabilization of emulsions is polar interactions (e.g. H-bonding) through the hydrophilic parts of the peptides. Those peptides with a preponderance of polar interaction groups distribution (i.e. NH2, COOH, imidazole) showed the highest interfacial activity under favorable pH conditions. This suggests that custom-made peptides whose hydrophilic/hydrophobic regions can be fine-tuned depending on the application can be easily produced with the additional advantage of their biodegradable nature.

Binding interactions of a series of sulfonated water-soluble resorcinarenes with bovine liver catalase.

Resorcinarenes are macrocyclic molecules that can bind different molecules in a supramolecular fashion. There are some sulfonated water-soluble derivatives that have been investigated to bind proteins avoiding fibrillation. The interaction with enzymes such as catalase (CAT) allows the interpretation of the possible effects of the use of resorcinarenes on human health or environmental applications. The interaction of five sulfonated resorcinarenes with different chemical structures was investigated by using different biophysical methods. The results of the spectroscopic experiments (fluorescence, synchronous fluorescence, and Uv-vis spectrophotometry) show different degrees of structural change, indicating that the binding of the macrocycles that were studied causes alterations on the conformation of CAT. The resorcinarenes reduce the activity of CAT in different extent, two macrocycles (named Na4EtRA and Na4PrRA, according to ethyl or propyl moieties at the lower pendant group) exhibit significant inhibition capacity (until ca. 70%). The study about inhibition types reveals a non-competitive mechanism for all the studied resorcinarenes. The docking calculations reveal that the macrocycles bond mainly to two domains of the CAT structure, which are not related with the active site.