Connection between Mechanical Relaxation and Equilibration Kinetics in a High-Entropy Metallic Glass.

The slow transition from an out-of-equilibrium glass towards a supercooled liquid is a complex relaxation phenomenon. In this Letter, we study the correlation between mechanical relaxation and equilibration kinetics in a Pd_{20}Pt_{20}Cu_{20}Ni_{20}P_{20} high-entropy metallic glass. The evolution of stress relaxation with aging time was obtained with an unprecedented detail, allowing us to pinpoint new interesting features. The long structural relaxation towards equilibrium contains a wide distribution of activation energies, instead of being just associated to the ß relaxation as commonly accepted. The stress relaxation time can be correlated with the equilibration rate and we observe a decrease of microstructural heterogeneity which contrasts with an increase of dynamic heterogeneity. These results significantly enhance our insight of the interplay between relaxation dynamics and thermodynamics in metallic glasses.

Alteraciones neuropsicológicas y hallazgos neurorradiológicos en pacientes con conmoción cerebral postraumática. Resultados de un estudio piloto / Neuropsychological alterations and neuroradiological findings in patients with post-traumatic concussion: Results of a pilot study

INTRODUCCIÓN: Los traumatismos craneoencefálicos leves (TCE-L) han sido tradicionalmente considerados acontecimientos sin repercusiones cerebrales significativas, cuya sintomatología remite espontáneamente en unos días. Sin embargo, estos hechos son cada vez más cuestionados. Este estudio pretende objetivar la existencia de alteraciones cognitivas precoces en una serie de pacientes con TCE-L y relacionar los hallazgos con distintos marcadores de lesión cerebral. MÉTODOS: Estudio prospectivo de una cohorte de pacientes con un TCE-L valorados de forma consecutiva durante 12 meses. De un total de 1.144 pacientes, se seleccionó a 41 (3,7%) que habían presentado una conmoción cerebral. Además de la valoración clínica habitual y de la práctica de una tomografía computarizada (TC) cerebral, los pacientes fueron estudiados mediante un test estandarizado para síntomas posconmocionales en las primeras 24h después del TCE-L y al cabo de 1-2 semanas y, coincidiendo con la segunda valoración, mediante una batería neuropsicológica. Los resultados se compararon con los de un grupo de 28 voluntarios sanos de características parecidas. En 20 pacientes se practicó una resonancia magnética (RM) craneal. RESULTADOS: En este análisis exploratorio, la memoria y el aprendizaje verbal fueron las funciones cognitivas más afectadas después del TCE-L. Siete de los 20 pacientes con TC cerebral normal presentaron alteraciones estructurales visibles por RM, que en 2 casos fueron compatibles con la presencia de lesión axonal difusa. CONCLUSIONES: Los resultados de este estudio piloto sugieren la presencia de alteraciones cognitivas precoces y lesiones cerebrales estructurales en un porcentaje no despreciable de pacientes que han presentado una conmoción cerebral recuperada después de un TCE-L

INTRODUCTION: Mild traumatic brain injury (mTBI) has traditionally been considered to cause no significant brain damage since symptoms spontaneously remit after a few days. However, this idea is facing increasing scrutiny. The purpose of this study is to demonstrate the presence of early cognitive alterations in a series of patients with mTBI and to link these findings to different markers of brain damage. METHODS: We conducted a prospective study of a consecutive series of patients with mTBI who were evaluated over a 12-month period. Forty-one (3.7%) of the 1144 included patients had experienced a concussion. Patients underwent a routine clinical evaluation and a brain computed tomography (CT) scan, and were also administered a standardised test for post-concussion symptoms within the first 24 hours of mTBI and also 1 to 2 weeks later. The second assessment also included a neuropsychological test battery. The results of these studies were compared to those of a control group of 28 healthy volunteers with similar characteristics. Twenty patients underwent an MRI scan. RESULTS: Verbal memory and learning were the cognitive functions most affected by mTBI. Seven out of the 20 patients with normal CT findings displayed structural alterations on MR images, which were compatible with diffuse axonal injury in 2 cases. CONCLUSIONS: Results from this pilot study suggest that early cognitive alterations and structural brain lesions affect a considerable percentage of patients with post-concussion syndrome following mTBI

Neuropsychological alterations and neuroradiological findings in patients with post-traumatic concussion: Results of a pilot study. / Alteraciones neuropsicológicas y hallazgos neurorradiológicos en pacientes con conmoción cerebral postraumática. Resultados de un estudio piloto.

INTRODUCTION: Mild traumatic brain injury (mTBI) has traditionally been considered to cause no significant brain damage since symptoms spontaneously remit after a few days. However, this idea is facing increasing scrutiny. The purpose of this study is to demonstrate the presence of early cognitive alterations in a series of patients with mTBI and to link these findings to different markers of brain damage. METHODS: We conducted a prospective study of a consecutive series of patients with mTBI who were evaluated over a 12-month period. Forty-one (3.7%) of the 1144 included patients had experienced a concussion. Patients underwent a routine clinical evaluation and a brain computed tomography (CT) scan, and were also administered a standardised test for post-concussion symptoms within the first 24hours of mTBI and also 1 to 2 weeks later. The second assessment also included a neuropsychological test battery. The results of these studies were compared to those of a control group of 28 healthy volunteers with similar characteristics. Twenty patients underwent an MRI scan. RESULTS: Verbal memory and learning were the cognitive functions most affected by mTBI. Seven out of the 20 patients with normal CT findings displayed structural alterations on MR images, which were compatible with diffuse axonal injury in 2 cases. CONCLUSIONS: Results from this pilot study suggest that early cognitive alterations and structural brain lesions affect a considerable percentage of patients with post-concussion syndrome following mTBI.

Determination of hydrocarbon types in petroleum and coal-derived products by thin-layer chromatography/densitometry.

Different methodologies based on thin-layer chromatography (TLC)/densitometry were used to separate and quantitate hydrocarbon types in middle distillates (gas oil), heavy distillates (lubricant) from petroleum, and coal-derived products. Thus, petroleum products were separated into saturates and aromatics by development, using n-hexane (9 min) followed by dichloromethane (4.5 min), of silica gel plates impregnated with berberine sulfate. Detection of saturates and aromatics was performed by fluorescence scanning using 365 nm as the excitation wavelength. Alternative detection of aromatics can be performed on either silica gel or berberine-impregnated plates by using ultraviolet (UV) densitometry at 250 nm. On the other hand, polar coal-derived products were separated into aromatics, polar compounds, and uneluted components by using silica gel plates and development with toluene (12 min), followed by dichloromethane-methanol (95 + 5, v/v), with detection by UV densitometry at 250 nm. In all cases, external standard calibration was used for quantitation. Results were validated by using standard methods or well-established techniques of the petrochemical industry. The potential usefulness of TLC/densitometry is discussed.

Berberine cation: A fluorescent chemosensor for alkanes and other low-polarity compounds. An explanation of this phenomenon

Alkanes in the presence of berberine sulfate provide an enhancement of fluorescent signal, which depends on alkane concentration and structure, when the system is irradiated with monochromatic UV light. Computational analysis suggests that an ion-induced dipole between alkanes and berberine sulfate is responsible for this phenomenon. This interaction can properly model the experimentally obtained fluorescent response. The proposed explanation allows other interacting systems to be designed, which have been experimentally confirmed.

Enhancement of fluorescence in thin-layer chromatography induced by the interaction between n-alkanes and an organic cation

Fluorescence enhancement of a broad variety of solutes has been used extensively in TLC although no thorough explanation has been proposed. In this work, we try to understand it and explore new applications to which it can be put. In this way, alkanes can be quantitatively determined by fluorescence scanning densitometry using silica gel plates impregnated with berberine sulfate. Molecular simulation and analysis of molecular orbitals allows this phenomenon to be explained in this case and lays the groundwork to explain fluorescence enhancements produced by other molecules. A ion-molecule interaction between alkanes and berberine sulfate is responsible for the enhancement of fluorescence produced by alkanes. Computational results suggest that the surrounding alkane molecules provide an apolar environment to the berberine cation, thus enhancing the intensity of the fluorescence signal. This proposed explanation has been tested by extending the fluorescence determination to other compounds. These include biologically interesting saturated and unsaturated fatty acids, steroids and derivatives, prostaglandins, ceramides, galactocerebrosides, as well as terpenes, and polypropylene glycols. In addition, according to the proposed explanation, the properties required for alternative impregnants to berberine are discussed.