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1.
Sensors (Basel) ; 24(6)2024 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-38544099

RESUMEN

A comparison of low-cost radon monitors was conducted at the Laboratory of Natural Radiation (LNR). The monitors we evaluated were EcoQube, RadonEye, RadonEye Plus2, Spirit, ViewPlus, ViewRadon and WavePlus. An AlphaGUARD monitor calibrated at the Laboratory of Environmental Radioactivity of the University of Cantabria (LaRUC), accredited for testing and calibration according to ISO/IEC 17025, provided the reference value of radon concentration. The temporal stability of the monitors was studied, obtaining a percentage of missing records ranged from 1% to 19% of the data. The main technical characteristics studied were temporal stability, measurement ranges, accuracy, correlation and response time. The main results show that the measurement ranges align with those specified by their manufacturers, with percentage differences with respect to the reference monitor of between 5% and 16%. The diversity found for response time is remarkable, with values ranging from 1 to 15 h, with Pearson correlation factors between 0.63 and 0.90.

2.
JACS Au ; 4(2): 744-759, 2024 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-38425934

RESUMEN

The tandem CO2 hydrogenation to hydrocarbons over mixed metal oxide/zeolite catalysts (OXZEO) is an efficient way of producing value-added hydrocarbons (platform chemicals and fuels) directly from CO2via methanol intermediate in a single reactor. In this contribution, two MAPO-18 zeotypes (M = Mg, Si) were tested and their performance was compared under methanol-to-olefins (MTO) conditions (350 °C, PCH3OH = 0.04 bar, 6.5 gCH3OH h-1 g-1), methanol/CO/H2 cofeed conditions (350 °C, PCH3OH/PCO/PH2 = 1:7.3:21.7 bar, 2.5 gCH3OH h-1 g-1), and tandem CO2 hydrogenation-to-olefin conditions (350 °C, PCO2/PH2 = 7.5:22.5 bar, 1.4-12.0 gMAPO-18 h molCO2-1). In the latter case, the zeotypes were mixed with a fixed amount of ZnO:ZrO2 catalyst, well-known for the conversion of CO2/H2 to methanol. Focus was set on the methanol conversion activity, product selectivity, and performance stability with time-on-stream. In situ and ex situ Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), sorption experiments, and ab initio molecular dynamics (AIMD) calculations were performed to correlate material performance with material characteristics. The catalytic tests demonstrated the better performance of MgAPO-18 versus SAPO-18 at MTO conditions, the much superior performance of MgAPO-18 under methanol/CO/H2 cofeeds, and yet the increasingly similar performance of the two materials under tandem conditions upon increasing the zeotype-to-oxide ratio in the tandem catalyst bed. In situ FT-IR measurements coupled with AIMD calculations revealed differences in the MTO initiation mechanism between the two materials. SAPO-18 promoted initial CO2 formation, indicative of a formaldehyde-based decarboxylation mechanism, while CO and ketene were the main constituents of the initiation pool in MgAPO-18, suggesting a decarbonylation mechanism. Under tandem CO2 hydrogenation conditions, the presence of high water concentrations and low methanol partial pressure in the reaction medium led to lower, and increasingly similar, methanol turnover frequencies for the zeotypes. Despite both MAPO-18 zeotypes showing signs of activity loss upon storage due to the interaction of the sites with ambient humidity, they presented a remarkable stability after reaching steady state under tandem reaction conditions and after steaming and regeneration cycles at high temperatures. Water adsorption experiments at room temperature confirmed this observation. The faster activity loss observed in the Mg version is assigned to its harder Mg2+-ion character and the higher concentration of CHA defects in the AEI structure, identified by solid-state NMR and XRD. The low stability of a MgAPO-34 zeotype (CHA structure) upon storage corroborated the relationship between CHA defects and instability.

3.
Nat Commun ; 15(1): 2045, 2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38448464

RESUMEN

Metal-organic frameworks have drawn attention as potential catalysts owing to their unique tunable surface chemistry and accessibility. However, their application in thermal catalysis has been limited because of their instability under harsh temperatures and pressures, such as the hydrogenation of CO2 to methanol. Herein, we use a controlled two-step method to synthesize finely dispersed Cu on a zeolitic imidazolate framework-8 (ZIF-8). This catalyst suffers a series of transformations during the CO2 hydrogenation to methanol, leading to ~14 nm Cu nanoparticles encapsulated on the Zn-based MOF that are highly active (2-fold higher methanol productivity than the commercial Cu-Zn-Al catalyst), very selective (>90%), and remarkably stable for over 150 h. In situ spectroscopy, density functional theory calculations, and kinetic results reveal the preferential adsorption sites, the preferential reaction pathways, and the reverse water gas shift reaction suppression over this catalyst. The developed material is robust, easy to synthesize, and active for CO2 utilization.

4.
Phys Rev E ; 109(1): L012102, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38366538

RESUMEN

The scaling behavior of the excited energy states of the directed polymer in random media is analyzed numerically. We find that the spatial correlations of polymer energies scale as ∼k^{-δ} for small enough wave numbers k with a nontrivial exponent δ≈1.3. The equivalence between the stochastic-field equation that describes the partition function of the directed polymer and that governing the time evolution of infinitesimal perturbations in space-time chaos is exploited to connect this exponent δ with the spatial correlations of the Lyapunov vectors reported in the literature. The relevance of our results for other problems involving optimization in random systems is discussed.

5.
Nanoscale ; 16(2): 664-677, 2024 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-38100059

RESUMEN

Graphene-based solution-gated field-effect transistors (gSGFETs) allow the quantification of the brain's full-band signal. Extracellular alternating current (AC) signals include local field potentials (LFP, population activity within a reach of hundreds of micrometers), multiunit activity (MUA), and ultimately single units. Direct current (DC) potentials are slow brain signals with a frequency under 0.1 Hz, and commonly filtered out by conventional AC amplifiers. This component conveys information about what has been referred to as "infraslow" activity. We used gSGFET arrays to record full-band patterns from both physiological and pathological activity generated by the cerebral cortex. To this end, we used an in vitro preparation of cerebral cortex that generates spontaneous rhythmic activity, such as that occurring in slow wave sleep. This examination extended to experimentally induced pathological activities, including epileptiform discharges and cortical spreading depression. Validation of recordings obtained via gSGFETs, including both AC and DC components, was accomplished by cross-referencing with well-established technologies, thereby quantifying these components across different activity patterns. We then explored an additional gSGFET potential application, which is the measure of externally induced electric fields such as those used in therapeutic neuromodulation in humans. Finally, we tested the gSGFETs in human cortical slices obtained intrasurgically. In conclusion, this study offers a comprehensive characterization of gSGFETs for brain recordings, with a focus on potential clinical applications of this emerging technology.


Asunto(s)
Grafito , Humanos , Corteza Cerebral , Encéfalo
6.
Rev. cuba. oftalmol ; 36(3)sept. 2023.
Artículo en Español | LILACS-Express | LILACS | ID: biblio-1550946

RESUMEN

Objetivo: Caracterizar las aberraciones corneales de bajo orden en pacientes con ametropías miópicas. Métodos: Se realizó un estudio descriptivo, observacional y transversal, con una muestra de 104 ojos de 104 pacientes adultos con ametropías miópicas y un grupo control de 104 ojos de 104 voluntarios emétropes, que asistieron a consulta de Cirugía Refractiva del Instituto Cubano de Oftalmología. Se definieron las variables demográficas, clínicas y para la cuantificación de las aberraciones corneales la elevación-depresión y el valor cuadrático medio, aportadas mediante el mapa aberrométrico del Pentacam HR. Resultados: Hubo un predominio del sexo femenino, el rango de edad estuvo comprendido entre 18 y 39 años en ambos grupos. La mediana del equivalente esférico de los pacientes de ametropías miópicas fue -3,25 dioptrías, con agudeza visual sin corrección de 0,10, esfera de -2,63 D y cilindro de -1,00 D, 91 ojos (87,50 %) tenían astigmatismo miópico compuesto. Los valores de elevación-depresión y el valor cuadrático medio de bajo orden fueron mayores en los pacientes con ametropías miópicas que los emétropes (p< 0,001). El astigmatismo vertical, desenfoque y el astigmatismo horizontal no presentaron diferencia estadísticamente significativa entre ambos grupos. Conclusiones: La miopía con o sin astigmatismo se debe estudiar y tratar como una aberración de bajo orden. Los valores de elevación-depresión y cuadrático medio son superiores en los ojos con ametropías miópicas respecto a los emétropes.


Objective: To characterize low-order corneal aberrations in patients with myopic ametropia. Methods: A descriptive, observational and cross-sectional study was carried out with a sample of 104 eyes of 104 adult patients with myopic ametropia and a control group of 104 eyes of 104 emmetropic volunteers, who attended the Refractive Surgery Clinic of the Cuban Institute of Ophthalmology. Demographic and clinical variables were defined, and for the quantification of corneal aberrations, elevation-depression and average square value, provided by means of the Pentacam HR aberrometric map. Results: There was a predominance of female sex, the age range was between 18 and 39 years in both groups. The median spherical equivalent of myopic ametropia patients was -3.25 diopters, with uncorrected visual acuity of 0.10, sphere of -2.63 D and cylinder of -1.00 D, 91 eyes (87.50%) had compound myopic astigmatism. Elevation-depression values and low-order root average square value were higher in patients with myopic ametropes than emmetropes (p< 0.001). Vertical astigmatism, defocus and horizontal astigmatism showed no statistically significant difference between the two groups. Conclusions: Myopia with or without astigmatism should be studied and treated as a low-order aberration. The elevation-depression and average square values are higher in eyes with myopic ametropia than in emmetropic eyes.

7.
Molecules ; 28(16)2023 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-37630347

RESUMEN

The formose reaction is an autocatalytic series of aldol condensations that allows one to obtain monosaccharides from formaldehyde. The formose reaction suffers from a lack of selectivity, which hinders practical applications at the industrial level. Over the years, many attempts have been made to overcome this selectivity issue, with modest results. Heterogeneous porous catalysts with acid-base properties, such as Metal-Organic Frameworks (MOFs), can offer advantages compared to homogeneous strong bases (e.g., calcium hydroxide) for increasing the selectivity of this important reaction. For the very first time, four different Zeolite Imidazolate Frameworks are presented in this work as catalysts for the formose reaction in liquid phase, and their catalytic performances were compared with those of the typical homogeneous catalyst (i.e., calcium hydroxide). The heterogeneous nature of the catalysis, the possible contribution of leached metal or linkers to the solution, and the stability of the materials were investigated. The porous structure of these solids and their mild basicity make them suitable for obtaining enhanced selectivity at 30% formaldehyde conversion. Most of the MOFs tested showed low structural stability under reaction conditions, thereby indicating the need to search for new MOF families with higher robustness. However, this important result opens the path for future research on porous heterogeneous basic catalysts for the formose reaction.

8.
Chem Mater ; 35(2): 692-699, 2023 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-37520114

RESUMEN

Zeolitic imidazolate frameworks (ZIFs) have been profusely used as catalysts for inserting CO2 into organic epoxides (i.e., epichlorohydrin) through cycloaddition. Here, we demonstrate that these materials suffer from irreversible degradation by leaching. To prove this, we performed the reactions and analyzed the final reaction mixtures by elemental analysis and the resulting materials by different microscopies. We found that the difference in catalytic activity between three ZIF-67 and one ZIF-L catalysts was related to the rate at which the materials degraded. Particularly, the {100} facet leaches faster than the others, regardless of the material used. The catalytic activity strongly depended on the amount of leached elements in the liquid phase since these species are extremely active. Our work points to the instability of these materials under relevant reaction conditions and the necessity of additional treatments to improve their stability.

9.
Int Orthop ; 47(11): 2869-2875, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37294431

RESUMEN

PURPOSE: The finding of severe skeletal alterations in ancient remains could give us useful information not only about the pathologies of the individual per se, as it could infer the state of health of a population. METHODS: From the findings of the Mudéjar Cemetery of Uceda (Guadalajara, Central Spain) where a total of 116 burials with almost complete skeleton were recovered, an interesting individual is presented (palaeopathological perspective). The individual 114UC corresponds to a male of 20-25 years old and its age goes back to the thirteenth-fourteenth centuries. RESULTS: The first inspection showed the presence of serious alterations especially in the lumbar spine and pelvic girdle. Seven vertebrae (from T11 to L5) showed an unusual posterior fusion only in the postzygapophyseal joints. The pelvis, after being accurately assembled and congruence verified by X-ray and CT scan, showed a noticeable asymmetry of both iliac wings together with a coxa magna protusa (Otto's pelvis), severe anteversion of both cup hips and osteochondritis of the right femoral head. The posterior-slope of both tibias reached about 10°. CONCLUSIONS: The differential diagnoses lead us to think of Arthrogryposis Multiplex Congenita as the most probable diagnosis. We analyzed the same biomechanical aspects after taking into account some patterns that give us information about a possible mobility in the first stage of life. We discuss the very few other cases described both from artworks and in the palaeopathological record. To our knowledge, this case could be the oldest published case of AMC worldwide.


Asunto(s)
Restos Mortales , Enfermedades Raras , Persona de Mediana Edad , Humanos , Masculino , Adulto Joven , Adulto , España/epidemiología , Tomografía Computarizada por Rayos X , Vértebras Lumbares
10.
Rev. cuba. oftalmol ; 36(2)jun. 2023.
Artículo en Español | LILACS-Express | LILACS | ID: biblio-1550917

RESUMEN

Objetivo: Determinar las aberraciones corneales en pacientes con indicación de cirugía refractiva con láser de excímeros. Métodos: Se realizó un estudio retrospectivo, transversal, descriptivo, con 161 ojos de 81 pacientes adultos, de ambos sexos con indicación de cirugía con láser de excímeros para la corrección de su defecto refractivo. Se definieron como variables edad, sexo, desenfoque, astigmatismo, coma, trefoil y aberración esférica, las que se determinaron por el estudio topográfico de rutina con el topógrafo KeratronTM Scout, Optikon. Resultados: Se obtuvieron los siguientes valores promedios: desenfoque -4,17 ± 0,29 D (-16,15 a 8,5 D) y absoluto 4,94 ± 0,199 (10 a 16,5 D), astigmatismo -1,56 ± 0,09 D (-9,44 a -0,09 D), coma 0,25 ± 0,016 (0,01 a 1,5 D), trefoil 0,204 ± 0,016 (0,01 a 1,18 D) y aberración esférica 0,316 ± 0,018 D (0,0 a 1,27D). En el 75 % de los casos los valores absolutos de desenfoque fueron inferiores a 6,56, de astigmatismo inferior a 0,33 D, de coma menor que 0,33, trefoil inferior a 0,25 y aberraciones esféricas menores que 0,32 D. Conclusiones: Los valores promedio de las aberraciones corneales desenfoque, astigmatismo, coma, trefoil y aberración esférica se encuentran en el rango de los valores reportados en la literatura científica y la distribución de los valores de las aberraciones corneales presentan desplazamiento de la mayoría de los casos hacia los valores más bajo del rango de determinación.


Objective: To determine corneal aberrations in patients indicated for excimer laser refractive surgery. Methods: A retrospective, cross-sectional and descriptive study was carried out with 161 eyes of 81 adult patients of both sexes with indication of excimer laser surgery for the correction of their refractive defect. Age, sex, defocus, astigmatism, coma, trefoil and spherical aberration were defined as variables, determined by routine topographic study with the KeratronTM Scout topographer, Optikon. Results: The following average values were obtained: defocus of -4.17 ± 0.29 D (-16.15 to 8.5 D) and absolute of 4.94 ± 0.199 (10 to 16.5 D), astigmatism of -1.56 ± 0.09 D (-9.44 to -0.09 D), coma of 0.25 ± 0.016 (0.01 to 1.5 D), trefoil of 0.204 ± 0.016 (0.01 to 1.18 D) and spherical aberration of 0.316 ± 0.018 D (0.0 to 1.27D). In 75 % of the cases, the absolute values for defocus were lower than 6.56; for astigmatism, lower than 0.33 D; for coma, lower than 0.33; for trefoil, lower than 0.25; and for spherical aberrations, lower than 0.32 D. Conclusions: The average values of corneal aberrations for defocus, astigmatism, coma, trefoil and spherical aberration are in the range of values reported in the scientific literature, while the distribution of corneal aberrations values present displacement of most of the cases towards the lower values of the determination range.

11.
Front Neurosci ; 17: 1096865, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37051148

RESUMEN

Introduction: Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that stimulates the auricular branch of the vagus nerve. The modulation of the locus coeruleus-norepinephrine (LC-NE) network is one of the potential working mechanisms of this method. Our aims were 1-to investigate if short and single applications of taVNS can modulate the P300 cognitive event-related potential (ERP) as an indirect marker that reflects NE brain activation under control of the LC, and 2-to evaluate the duration of these changes. Methods: 20 healthy volunteers executed an auditory oddball paradigm to obtain P300 and reaction time (RT) values. Then a 7 min active or sham taVNS period was initiated and simultaneously a new P300 paradigm was performed. We successively repeated the paradigm on 4 occasions with different time intervals up to 56 min after the stimulation onset. Results: During active taVNS an immediate and significant effect of increasing the amplitude and reducing the latency of P300, as well as a shortening in the RT was observed. This effect was prolonged in time up to 28 min. The values then returned to pre-stimulation levels. Sham stimulation did not generate changes. Discussion: Our results, demonstrate differential facilitating effects in a concrete time window after taVNS. Literature about the modulatory effect of taVNS over P300 ERP shows a wide spread of results. There is not a standardized system for taVNS and currently the great heterogeneity of stimulation approaches concerning targets and parameters, make it difficult to obtain conclusions about this relationship. Our study was designed optimizing several stimulation settings, such as a customized earbud stimulator, enlarged stimulating surface, simultaneous stimulation over the cymba and cavum conchae, a Delayed Biphasic Pulse Burst and current controlled stimulation that adjusted the output voltage and guaranteed the administration of a preset electrical dose. Under our stimulation conditions, targeting vagal nerve fibers via taVNS modulates the P300 in healthy participants. The optimal settings of modulatory function of taVNS on P300, and their interdependency is insufficiently studied in the literature, but our data provides several easily optimizable parameters, that will produce more robust results in future.

12.
Materials (Basel) ; 16(5)2023 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-36903150

RESUMEN

SiC is one of the most important ceramics at present due to its excellent properties and wide range of applications. The industrial production method, known as the Acheson method, has not changed in 125 years. Because the synthesis method in the laboratory is completely different, laboratory optimisation may not be extrapolated to the industrial level. In the present study, the results at the industrial level and at the laboratory level of the synthesis of SiC are compared. These results show that it is necessary to make a more detailed analysis of the coke than the traditional one; therefore, the Optical Texture Index (OTI) should be included, as well as the analysis of the metals that form the ashes. It has been found that the main influencing factors are OTI and the presence of Fe and Ni in the ashes. It has been determined that the higher the OTI, as well as the Fe and Ni content, the better the results obtained. Therefore, the use of regular coke is recommended in the industrial synthesis of SiC.

13.
Small Methods ; 7(4): e2201413, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36789569

RESUMEN

Metal-organic frameworks (MOFs) are porous hybrid materials with countless potential applications. Most of these rely on their porous structure, tunable composition, and the possibility of incorporating and expanding their functions. Although functionalization of the inner surface of MOF crystals has received considerable attention in recent years, methods to functionalize selectively the outer crystal surface of MOFs are developed to a lesser extent, despite their importance. This article summarizes different types of post-synthetic modifications and possible applications of modified materials such as: catalysis, adsorption, drug delivery, mixed matrix membranes, and stabilization of porous liquids.

14.
Forensic Sci Int ; 343: 111568, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36682240

RESUMEN

The Death Certificate (DC) is an important medical-legal. However, despite its importance, the professionals involved are not well trained and consequently there exist many errors in completion. This situation can cause misclassification in mortality statistics, but also it means that many natural deaths end up being studied by the medical examiner, entailing a waste of resources. An analysis of 1974 DCs in Madrid is carried out to assess the quality of the completion, discover the main errors in the certificates and analyse possible improvement strategies. The study highlights that the demographic and personal information about the deceased is mostly correct; in 16,2 % of the cases the official document was not used; 91 % of the DCs in the sample have a certain degree of error (major or minor); and 38,4 % of the documents chain of causes were incorrect. The main measure proposed is increased training for certifiers, which should begin with activities at undergraduate level and continue later with periodic training workshops. In addition, we consider it essential to digitalise DCs in Spain. This would greatly facilitate completion. It is also proposed that medical examiners use, in Spain, a document similar to the official DC so that the statistics of violent and natural deaths which have required the medical examiners' intervention will improve.


Asunto(s)
Médicos Forenses , Certificado de Defunción , Humanos , Causas de Muerte , España
15.
Pathobiology ; 90(1): 56-62, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-35504265

RESUMEN

INTRODUCTION: Acute plastic deformation refers to a traumatic bending or bowing without a detectable cortical defect. CASE PRESENTATION AND DISCUSSION: We describe a rare case from an individual that was exhumed from the Hispano-Mudejar necropolis in Uceda (Guadalajara, Spain) dated between the 13th and 14th centuries AD. The case corresponds to an adult woman, with a bowing involvement of the left ulna and radius. After making the differential diagnosis with various pathologies likely to present with this alteration, we reached the diagnosis of acute plastic deformation of the forearm through external and radiological examination and comparison with the healthy contralateral forearm. CONCLUSIONS: Acute plastic deformation is a rare traumatic injury, not described until the last century and only rarely described in palaeopathological contexts. We contribute a new case, the first being sufficiently documented, contributing to the knowledge and diagnosis of this type of trauma in the ancient bone, while deepening the knowledge of the living conditions of the medieval Mudejar population of Uceda.


Asunto(s)
Traumatismos del Antebrazo , Antebrazo , Adulto , Femenino , Humanos , Antebrazo/patología , Traumatismos del Antebrazo/patología , Historia Medieval , Radio (Anatomía)/lesiones , Radio (Anatomía)/patología , Cúbito/lesiones , Cúbito/patología
16.
Asian J Surg ; 46(3): 1187-1192, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36041893

RESUMEN

INTRODUCTION: There are still controversies regarding the time of surgical management for acute appendicitis (AA). The main objective of this study was to recognize the surgical deferral time in patients with acute appendicitis and its relationship with the severity of presentation. MATERIALS AND METHODS: We performed a retrospective review of prospectively collected data of all patients with acute appendicitis undergoing appendectomy from August 2018 to August 2020 in an academic, public hospital. Elapsed time from arrival to the emergency room to skin incision was determined. Patients were divided into three groups based on the elapsed time: less than 6 h, between 6 and 12 h, and more than 12 h. RESULTS: A total of 782 patients were included. Of them, 443 (56.6%) patients had a surgical deferral time of less than 6 h, 238 (30.4%) patients between 6 and 12 h, and 101 (13%) patients of more than 12 h. Patients with more than 12 h of surgical deferral time had a more complicated clinical presentation (P = 0.013), a higher frequency of abscess formation (P = 0.022), higher requirement for the use of surgical drainage (P = 0.018), and longer length of hospital stay (P = <0.001). CONCLUSION: Surgical deferral >12 h was associated with a higher incidence of complicated appendicitis, intra-abdominal abscesses, and overall hospital stay. However, in the multivariate analysis, only total evolution time, from the first symptom to surgery, was a significant independent predictor of complicated appendicitis.


Asunto(s)
Absceso Abdominal , Apendicitis , Humanos , Complicaciones Posoperatorias/epidemiología , Apendicitis/diagnóstico , Apendicitis/cirugía , Apendicitis/complicaciones , Absceso Abdominal/complicaciones , Enfermedad Aguda , Apendicectomía
17.
In. Cárdenas Díaz, Taimi. Óptica y optometría. Principios y aplicación clínica. Volumen 1. La Habana, Editorial Ciencias Médicas, 2023. , ilus.
Monografía en Español | CUMED | ID: cum-79185
18.
J Funct Biomater ; 13(4)2022 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-36547557

RESUMEN

The development and evaluation of scaffolds play a crucial role in the engineering of hyaline cartilage tissue. This work aims to evaluate the performance of silk fibroin hydrogels fabricated from the cocoons of the Colombian hybrid in the in vitro regeneration of hyaline cartilage. The scaffolds were physicochemically characterized, and their performance was evaluated in a cellular model. The results showed that the scaffolds were rich in random coils and ß-sheets in their structure and susceptible to various serine proteases with different degradation profiles. Furthermore, they showed a significant increase in ACAN, COL10A1, and COL2A1 expression compared to pellet culture alone and allowed GAG deposition. The soluble portion of the scaffold did not affect chondrogenesis. Furthermore, they promoted the increase in COL1A2, showing a slight tendency to differentiate towards fibrous cartilage. The results also showed that Colombian silk could be used as a source of biomedical devices, paving the way for sericulture to become a more diverse economic activity in emerging countries.

19.
Molecules ; 27(22)2022 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-36431891

RESUMEN

One way to exploit CO2 is to use it as a feedstock for the production of cyclic carbonates via its reaction with organic epoxides. As far as we know, there is still no heterogeneous catalyst that accelerates the reaction in a selective, efficient and industrially usable way. Cobalt and zinc-based zeolitic imidazole frameworks (ZIFs) have been explored as heterogeneous catalysts for this reaction. In particular, we have prepared ZIF-8 and ZIF-67 catalysts, which have been modified by partial replacement of 2-methylimidazole by 1,2,4-triazole, in order to introduce uncoordinated nitrogen groups with the metal. The catalysts have shown very good catalytic performance, within the best of the heterogeneous catalysts tested in the cycloaddition of CO2 with epichlorohydrin. The catalytic activity is due ultimately to defects on the outer surface of the crystal, and varies in the order of ZIF-67-m > ZIF-67 > ZiF-8-m = ZIF-8. Notably, reactions take place under mild reaction conditions and without the use of co-catalysts.

20.
Phys Rev E ; 106(2-1): 024802, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36109999

RESUMEN

The one-dimensional Kardar-Parisi-Zhang (KPZ) equation is becoming an overarching paradigm for the scaling of nonequilibrium, spatially extended, classical and quantum systems with strong correlations. Recent analytical solutions have uncovered a rich structure regarding its scaling exponents and fluctuation statistics. However, the zero surface tension or zero viscosity case eludes such analytical solutions and has remained ill-understood. Using numerical simulations, we elucidate a well-defined universality class for this case that differs from that of the viscous case, featuring intrinsically anomalous kinetic roughening (despite previous expectations for systems with local interactions and time-dependent noise) and ballistic dynamics. The latter may be relevant to recent quantum spin chain experiments which measure KPZ and ballistic relaxation under different conditions. We identify the ensuing set of scaling exponents in previous discrete interface growth models related with isotropic percolation, and show it to describe the fluctuations of additional continuum systems related with the noisy Korteweg-de Vries equation. Along this process, we additionally elucidate the universality class of the related inviscid stochastic Burgers equation.

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