Effects of Linear Deformation on Relaxation Time and Some Fermi Properties of Metals

In this work, a model for computing the relaxation time, Fermi velocity and Fermi temperature of deformed metals was developed based on free electron theory. This study generalized the work of Kiejna and Pogosov (2000) due to the shortcomings of the electron density parameter of deformed metals. They failed to account for metal dilation by assuming a constant value for the Poisson ratio of metals which leads to neglect of the uniaxial strain (deformation) in their computation. This causes the electron density parameter of both deformed and undeformed metals to be equal. The result obtained in this work revealed that there is an agreement between the experimental and computed values of the Fermi velocity, Fermi temperature and relaxation time of some of the metals calculated which shows the validity of the model used in the study. The experimental value used in this work is theoretically obtained by substituting the experimental value of Fermi energy obtained from solid state Physics by Charles Kittel (1976) into the model used in the computation. The Fermi velocity, Fermi temperature and relaxation time of all the metals subjected to different deformation decreases as deformation increases. This seems to suggest that as deformation increases the collision frequency between the interacting electron decreases which forces the relaxation time, Fermi velocity and Fermi temperature to decrease as deformation increases. This behavior could also be due to an increase in the inter-atomic spacing between the interacting electrons in the metals during deformation which reduces the strength of interaction between the electrons in metal and their-by forces the relaxation time, Fermi velocity and Fermi temperature to decrease as deformation increases. Keywords: relaxation time, Fermi velocity, Fermi temperature, mean free path, deformation, Fermi surface DOI: 10.7176/JNSR/9-8-04 Publication date: April 30th 201

Peak particle velocity data acquisition for monitoring blast induced earthquakes in quarry sites

The peak particle velocity datasets recorded during quarry blasts in the neighborhood villages and towns in Ibadan and Abeokuta were processed and analyzed in order to recommend a safe blast design for each of the quarries. The minimum peak particle velocity of 48.27 mm/s was recorded near the foundation of the nearest residence at the shot to monitored distance of 500m. The tendency of ground vibration emanating from the quarry sites to cause damage to the structures in the nearby dwelling areas is very high. The peak particle velocity datasets recorded were not within the safe limit. Therefore the peak particle velocity that will not exceed 35 mm/s is recommended for a safe blast design

Work function of elemental metals and its face dependence: Stabilized Jellium approach

The stabilizing potentials and work functions of elemental metals were calculated for the flat surface, the (111), (100) and (110) faces using the stabilized jellium model. The calculated work functions were compared with experimental values and calculated values obtained using the ab initio method. The stabilizing potentials for the different faces of the metals revealed that the less densely packed faces require higher potential for stabilization in the stabilized jellium model. The calculated work functions for the flat surface of the metals were in perfect agreement with experimental values for metals in the low-density limit and the agreement with experimental values decreased towards the high-density limit. The calculated work functions for the body centred cubic metals were in good agreement with experimental values. The calculated work function for the hexagonal close packed metals were in fairly good agreement with experimental values while the degree of agreement with experimental values was least for face centred cubic metals. The work functions of metals calculated in this work revealed that the more closely packed faces have higher work functions. The results obtained in this work revealed that the stabilized jellium model could be used to predict fairly well the work function of metals and calculate other metallic properties. JONAMP Vol. 11 2007: pp. 445-45

Stabilized jellium model-derived surface stress of metals

No Abstract.Nigerian Journal of Physics Vol. 20 (1) 2008: pp.6-1

Comparison of Calculated Work Function of Metals Using Metallic Plasma Model with Stabilized Jellium, Ab-Initio Approach and Experimental Values

"El sistema vestibular es el encargado de censar las fuerzas asociadas con la gravedad y el movimiento de la cabeza en los organismos y contribuye con la percepción y conciencia espacial en primera persona. El sistema vestibular envía información hacia el sistema nervioso central mediante los núcleos vestibulares y haciendo contacto de forma directa con el cerebelo. Las neuronas aferentes vestibulares (NAV) son las vías de conducción primaria de impulsos generados en la sinapsis con las células ciliadas, estas neuronas tienen sus cuerpos alojados en el ganglio de Scarpa y se han categorizado dos tipos de neuronas aferentes vestibulares, de acuerdo con el patrón de disparo que presentan pueden ser regulares e irregulares, y mantienen una actividad eléctrica basal debido a la sumación de potenciales postsinápticos excitatorios (EPSPs). Se ha propuesto que la corriente de sodio persistente (INap) puede estar contribuyendo con los EPSPs como se ha descrito en otras neuronas con actividad marcapasos sin embargo hasta el momento no se ha descrito la INap en las NAV. Utilizando la técnica de fijación de voltaje en su modalidad de célula completa en cultivo primario de NAV decidimos analizar si estas neuronas presentan la INap.

Tailoring the energy harvesting capacity of zinc selenide semiconductor nanomaterial through optical band gap modeling using genetically optimized intelligent method

Zinc selenide (ZnSe) nanomaterial is a binary semiconducting material with unique features, such as high chemical stability, high photosensitivity, low cost, great excitation binding energy, non-toxicity, and a tunable direct wide band gap. These characteristics contribute significantly to its wide usage as sensors, optical filters, photo-catalysts, optical recording materials, and photovoltaics, among others. The light energy harvesting capacity of this material can be enhanced and tailored to meet the required application demand through band gap tuning with compositional modulation, which influences the nano-structural size, as well as the crystal distortion of the semiconductor. This present work provides novel ways whereby the wide energy band gap of zinc selenide can be effectively modulated and tuned for light energy harvesting capacity enhancement by hybridizing a support vector regression algorithm (SVR) with a genetic algorithm (GA) for parameter combinatory optimization. The effectiveness of the SVR-GA model is compared with the stepwise regression (SPR)-based model using several performance evaluation metrics. The developed SVR-GA model outperforms the SPR model using the root mean square error metric, with a performance improvement of 33.68%, while a similar performance superiority is demonstrated by the SVR-GA model over the SPR using other performance metrics. The intelligent zinc selenide energy band gap modulation proposed in this work will facilitate the fabrication of zinc selenide-based sensors with enhanced light energy harvesting capacity at a reduced cost, with the circumvention of experimental stress