Mechanism of interaction between hydroxypropyl cellulose and water in aqueous solutions: Importance of polymer chain length

The utilization of hydroxypropyl cellulose (HPC) can be regarded as unexpected with regard to certain applications, such as being employed as a solubility enhancer for poorly soluble drugs and as a solubilizing agent for nano‐suspensions and amorphous solid dispersions. However, the best results were obtained for low‐molecular weight (Mw) HPC grades with a short‐chain structure. Therefore, in this study, seven grades of HPC with different polymer chain lengths (Mw) are analyzed in various aqueous solutions by a combination of 1H quantitative NMR spectroscopy, diffusion NMR spectroscopy, and water ligand observed via gradient spectroscopy; these investigations provide insights into the remarkable solubilizing property of HPC at the molecular and supramolecular levels. Furthermore, the hydration and the water residence time are found to be strongly dependent on the polymer chain length of HPC. The quantitative results obtained herein indicate that HPCs with shorter chain lengths retain smaller amounts of water around their hydrated molecules, as compared to their counterparts with longer chain lengthsS

14N NMR spectroscopy study of binding interaction between sodium azide and hydrated fullerene

Our study is the first attempt to study the interaction between NaN3 and hydrated fullerenes C60 by means of a non-chemical reaction-based approach. The aim is to study deviations of signals obtained by 14N NMR spectroscopy to detect the binding interaction between sodium azide and hydrated fullerene. We considered 14N NMR spectroscopy as one of the most suitable methods for the characterization of azides to show resonance signals corresponding to the three non-equivalent nitrogen atoms. The results demonstrate that there are changes in the chemical shift positions and line-broadening, which are related to the different molar ratios of NaN3:C60 in the samplesThe authors express gratefulness for financial support company Chemanteck (Galicia) and its founders Raquel Sendón García, Ana Rodríguez Bernaldo de QuirósS

Transfer learning or design a custom CNN for tactile object recognition

International Workshop on Robotac: New Progress in Tactile Perception and Learning in RoboticsNovel tactile sensors allow treating pressure lectures as standard images due to its highresolution. Therefore, computer vision algorithms such as Convolutional Neural Networks (CNNs) can be used to identify objects in contact. In this work, a high-resolution tactile sensor has been attached to a robotic end-effector to identify objects in contact. Moreover, two CNNs-based approaches have been tested in an experiment of classification of pressure images. These methods include a transfer learning approach using a pre-trained CNN on an RGB images dataset and a custom-made CNN trained from scratch with tactile information. A comparative study of performance between them has been carried out.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Spanish project DPI2015-65186-R, the European Commission under grant agreement BES-2016-078237, the educational project PIE-118 of the University of Malag

Mathematical and Numerical Modeling in Maritime Geomechanics

A theoretical and numerical framework to model the foundation of marine offshore structures is presented. The theoretical model is composed by a system of partial differential equations describing coupling between seabed solid skeleton and pore fluids (water, air, oil,…) combined with a system of ordinary differential equations describing the specific constitutive relation of the seabed soil skeleton. Once the theoretical model is described, the finite element numerical procedure to achieve an approximate solution of the governing equations is outlined. In order to validate the proposed theoretical and numerical framework the seaward tilt mechanism induced by the action of breaking waves over a vertical breakwater is numerically reproduced. The results numerically attained are in agreement with the main conclusions drawn from the literature associated with this failure mechanis

FTCS finite difference scheme GPGPU parallel computing for the heat conduction equation = Programación en paralelo GPGPU del método en diferencias finitas FTCS para la ecuación del calor

En el presente artículo se muestran las ventajas de la programación en paralelo resolviendo numéricamente la ecuación del calor en dos dimensiones a través del método de diferencias finitas explícito centrado en el espacio FTCS. De las conclusiones de este trabajo se pone de manifiesto la importancia de la programación en paralelo para tratar problemas grandes, en los que se requiere un elevado número de cálculos, para los cuales la programación secuencial resulta impracticable por el elevado tiempo de ejecución. En la primera sección se describe brevemente los conceptos básicos de programación en paralelo. Seguidamente se resume el método de diferencias finitas explícito centrado en el espacio FTCS aplicado a la ecuación parabólica del calor. Seguidamente se describe el problema de condiciones de contorno y valores iniciales específico al que se va a aplicar el método de diferencias finitas FTCS, proporcionando pseudocódigos de una implementación secuencial y dos implementaciones en paralelo. Finalmente tras la discusión de los resultados se presentan algunas conclusiones. In this paper the advantages of parallel computing are shown by solving the heat conduction equation in two dimensions with the forward in time central in space (FTCS) finite difference method. Two different levels of parallelization are consider and compared with traditional serial procedures. We show in this work the importance of parallel computing when dealing with large problems that are impractical or impossible to solve them with a serial computing procedure. In the first section a summary of parallel computing approach is presented. Subsequently, the forward in time central in space (FTCS) finite difference method for the heat conduction equation is outline, describing how the heat flow equation is derived in two dimensions and the particularities of the finite difference numerical technique considered. Then, a specific initial boundary value problem is solved by the FTCS finite difference method and serial and parallel pseudo codes are provided. Finally after results are discussed some conclusions are presented

Self-Association and Stereoselectivity in a Chiral Liquid-Crystal Colesteric Polymer Formed under Achiral Conditions

A cholesteric, chiral, liquid-crystal polyester PTOBEE [C26H20O8]n, synthesized from the racemic mixture of their starting materials, showed an unexpected stereoselective separation of polymer units which incorporate a higher excess of one enantiomer at the expenses of the other when the polycondensation reaction products are decanted into a large excess of toluene. An NMR diffusion study of PTOBEE obtained for a sample with 67% enantiomeric excess (ee) showed the formation of a complex by self-association of several polymer units with an unexpected higher tendency of the complex to be formed when the sample is further diluted. Cross saturation transferred NMR experiments showed the high stability of this complex and provided evidence of slow exchange equilibrium with the single polymer unit. The results suggest that both effects, the enantiomeric excess obtained after decantation in toluene, which was higher in the second fraction of the precipitate, and the high tendency of the complex formation in diluted samples of this polymer could be related. Polymer units incorporating a certain excess of one of the enantiomers could result in a privileged spatial geometry of the substituents which favors its self- aggregation, resulting in its precipitation during the synthetic process at two different kinetic rates.Peer reviewe

Functional diversity of motoneurons in the oculomotor system

Extraocular muscles contain two types of muscle fibers according to their innervation pattern: singly innervated muscle fibers (SIFs), similar to most skeletal muscle fibers, and multiply innervated muscle fibers (MIFs). Morphological studies have revealed that SIF and MIF motoneurons are segregated anatomically and receive different proportions of certain afferents, suggesting that while SIF motoneurons would participate in the whole repertoire of eye movements, MIF motoneurons would contribute only to slow eye movements and fixations. We have tested that proposal by performing single-unit recordings, in alert behaving cats, of electrophysiologically identified MIF and SIF motoneurons in the abducens nucleus. Our results show that both types of motoneuron discharge in relation to eye position and velocity, displaying a tonic–phasic firing pattern for different types of eye movement (saccades, vestibulo-ocular reflex, vergence) and gaze-holding. However, MIF motoneurons presented an overall reduced firing rate compared with SIF motoneurons, and had significantly lower recruitment threshold and also lower eye position and velocity sensitivities. Accordingly, MIF motoneurons could control mainly gaze in the off-direction, when less force is needed, whereas SIF motoneurons would contribute to increase muscle tension progressively toward the on-direction as more force is required. Anatomically, MIF and SIF motoneurons distributed intermingled within the abducens nucleus, with MIF motoneurons being smaller and having a lesser somatic synaptic coverage. Our data demonstrate the functional participation of both MIF and SIF motoneurons in fixations and slow and phasic eye movements, although their discharge properties indicate a functional segregation.Ministerio de Ciencia, Innovación y Universidades – Fondo Europeo de Desarrollo Regional (BFU2015-64515-P)Junta de Andalucía (BIO-297

Divergencias del alumnado y del profesorado universitario sobre las dificultades para aplicar la evaluación formativa

La evaluación formativa supone un claro cambio en la forma de plantear la evaluación en la docencia universitaria. Su aplicación no está exenta de cierta controversia, y sobre todo de dificultades, que hacen que alumnado y profesorado tengan distintas perspectivas. El objetivo del presente estudio ha sido comprobar las divergencias del alumnado y del profesorado cuando se diseña y se ponen en práctica sistemas de evaluación formativa. Se ha utilizado un cuestionario para el alumnado (N=3013) y los informes elaborados por el profesorado (N=46) aplicados durante el curso 2012-13. Los resultados muestran que la evaluación formativa es bastante exigente para el alumnado, aunque también muestran una alta satisfacción del alumnado con la misma, particularmente con la calificación. Un inconveniente que refleja el alumnado parece ser la acumulación de trabajo al final del proceso, lo cual resulta paradójico y requiere de una investigación más profunda en el futuro. El profesorado también muestra una alta satisfacción con este tipo de evaluación, aunque tengan una mayor carga de trabajo. Se observan escasas discrepancias entre los dos colectivos (alumnado y profesorado). En el estudio se proponen recomendaciones de puesta en práctica en cuanto al diseño y la planificación para investigaciones futuras. Las limitaciones se observan en cuanto a la población participante en el estudio, con el fin de que puedan generalizarse los resultados.Formative Assessment shows a clear change in how to approach the evaluation of university teaching. The application of Formative Assessment is not without some controversy, and above all difficulties due to students and teachers having different perspectives. The objective of the present study was to check the differences of students and teachers when formative assessment systems are designed and put into practice. A questionnaire was used for students (N = 3013) and a report prepared by the teachers (N = 46). Both were taken from the academic year 2012-13. The results show that formative assessment is quite demanding for students, but also that students are highly satisfied with it, particularly with grades. A problem that the students reflect seems to be the accumulation of work at the end of the process, which is paradoxical and will requires further research in the future. Teachers also show a high satisfaction with this type of assessment, even if they have a greater workload. There are few differences between the two groups (students and teachers). The study proposes recommendations for implementation in terms of design and planning for future research. The limitations of the research can be seen in terms of participating in the study population, so the results can be generalized

Toward a local maximum-entropy material point method at finite strain within a B-free approach

The material point method can be regarded as a meshfree extension of the finite element method. This fact has two interesting consequences. On the one hand, this puts a vast literature at our disposal. On the other hand, many of this inheritance has been adopted without questioning it. A clear example of it is the use of the Voigt algebra, which introduces an artificial break point between the formulation of the continuum problem and its discretized counterpart. In the authors' opinion, the use of the Voigt rules leads to a cumbersome formulation where the physical sense of the operations is obscured since the well-known algebra rules are lost. And with them, the intuition about how stresses and strains are related. To illustrate it, we will describe gently and meticulously the whole process to solve the nonlinear governing equations for isothermal finite strain elastodynamics, concluding with a compact set of expressions ready to be implemented effortless. In addition, the classic Newmark- (Formula presented.) algorithm has been accommodated to the local maximum-entropy material point method framework by means of an incremental formulation.Fil: Molinos, Miguel. Universidad Politécnica de Madrid; EspañaFil: Martín Stickle, Miguel. Universidad Politécnica de Madrid; EspañaFil: Navas, Pedro. Universidad Politécnica de Madrid; EspañaFil: Yagüe, Ángel. Universidad Politécnica de Madrid; EspañaFil: Manzanal, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad Politécnica de Madrid; EspañaFil: Pastor, Manuel. Universidad Politécnica de Madrid; Españ