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The effects of tensile strain on the current-voltage (I-V) characteristics of hydrogenated-edge armchair graphene nanoribbons are investigated by using DFT theory. The strain is introduced in two different ways related to the two types of systems studied in this work: in-plane strained systems (A) and out-of-plane strained systems due to bending (B). These two kinds of strain lead to make a distinction among three cases: in-plane strained systems with strained electrodes (A1) and with unstrained electrodes (A2), and out-of-plane homogeneously strained systems with unstrained, fixed electrodes (B). The systematic simulations to calculate the electronic transmission between two electrodes were focused on systems of 8 and 11 dimers in width. The results show that the differences between cases A2 and B are negligible, even though the strain mechanisms are different: in the plane case, the strain is uniaxial along its length; while in the bent case, the strain is caused by the arc deformation. Based on the study, a new type of nanoelectromechanical system solid state switching device is proposed. [ABSTRACT FROM AUTHOR]

We calculate the conduction miniband energy dispersion relation in an edge-defined silicon quantum wire periodic nanostructure embedded in SiO2. Our main aim is to predict the behavior of these nanostructures when used as components in optoelectronic devices such as, for example, photodetectors or intermediate-band solar cells. We take into consideration the effects of nonparabolicity and anisotropy and the different electron states arising from each valley when solving the Schrödinger equation. From these results, we investigate the intraband photon absorption coefficient for those transitions between minibands arising from the conduction band. We analyze the influence of light polarization and level of doping of the system in order to ascertain the best conditions for operation. [ABSTRACT FROM AUTHOR]

In this work, we propose a correction to the effective mass approach (EMA) to be used in Si quantum dot simulations. This correction tries to connect the different ways of modeling quantum dots within tight binding (considering the actual positions of the atoms and using additional atoms to passivate the surfaces) with those within the EMA, adapting the size of the simulated quantum dots to take the difference into account. With this aim, we implemented a 6×6 k·p calculation for the valence band and used a nonparabolic and anisotropic model for the conduction band to study hole and electron confinement, respectively. We then tested and used a very fast computational algorithm to obtain the electron and hole spectra in both cubic- and spherical-shaped quantum dots. [ABSTRACT FROM AUTHOR]

In this work we formulate the nonparabolic Schrödinger equation for a quantum dot in order to explore the main features of the carriers in these systems. In addition, we present a fast iterative numerical algorithm to solve it, obtaining the energy levels and envelope functions. We also model the electrostatic potential profile in a manner that makes it possible to discuss the effects of stronger confinements on the results. To demonstrate a practical implementation of this algorithm, we carry out an investigation into the effects of nonparabolicity of the valence band on the eigenstates of a Si quantum dot. Finally, we fit our results, using power expressions to relate the energy levels to the size of the cubic quantum dots, thus demonstrating the relevance of nonparabolicity. [ABSTRACT FROM AUTHOR]

In this paper we develop a suitable method for solving the effective-mass Schrödinger equation for two-dimensional electron and hole gases in semiconductor structures such as quantum wells using a general nonparabolic band structure. We present two different ways to treat barriers, the first being the exact solution and the second a suitable option when the band structure is not determined inside the gap. As a first application, this procedure was implemented to solve the effective-mass Schrödinger equation for holes in Si and Ge using an analytical valence-band model. Analyzing the results obtained enabled us to demonstrate the importance of nonparabolicity in energy quantization in these systems and to discuss the suitability of each of these two procedures for dealing with barriers. [ABSTRACT FROM AUTHOR]

Hole mobility over a wide range of temperatures in pure Si and Ge is studied within the framework of effective mass theory using the Monte Carlo method. With this aim, we have implemented a three-band model (heavy, light, and split-off holes) introducing nonparabolicity even for the latter, which is usually considered parabolic in the literature. The warping in the heavy and light bands was taken into account, maintaining a spherical model for the split-off band. We also developed scattering rate expressions to be used in a Monte Carlo procedure with the nonparabolicity and warping effects included explicitly in the scattering rate expressions, an aspect neglected in the literature. In so doing, we calculated exactly the nonparabolicity functions for the valence band from the expressions provided by Kane [J. Phys. Chem. Solids 1, 82 (1956)]. Further, we modeled the acoustic phonons on an inelastic mechanism, generalizing previous work, and applying a temperature-dependent average to obtain typical values of the energy of the acoustic phonons involved in the scattering processes. We show that our treatment of hole transport provides results close to those reported experimentally and comparable to those obtained with more complex methods, but requiring much less computing time. [ABSTRACT FROM AUTHOR]

Summary: Intramuscular fat (IMF) is one of the main meat quality traits for breeding programmes in livestock species. The main objective of this study was to identify genomic regions associated with IMF content comparing two rabbit populations divergently selected for this trait, and to generate a list of putative candidate genes. Animals were genotyped using the Affymetrix Axiom OrcunSNP Array (200k). After quality control, the data involved 477 animals and 93 540 SNPs. Two methods were used in this research: single marker regressions with the data adjusted by genomic relatedness, and a Bayesian multiple marker regression. Associated genomic regions were located on the rabbit chromosomes (OCU) OCU1, OCU8 and OCU13. The highest value for the percentage of the genomic variance explained by a genomic region was found in two consecutive genomic windows on OCU8 (7.34%). Genes in the associated regions of OCU1 and OCU8 presented biological functions related to the control of adipose cell function, lipid binding, transportation and localisation (APOLD1, PLBD1, PDE6H, GPRC5D and GPRC5A) and lipid metabolic processes (MTMR2). The EWSR1 gene, underlying the OCU13 region, is linked to the development of brown adipocytes. The findings suggest that there is a large component of polygenic effect behind the differences in IMF content in these two lines, as the variance explained by most of the windows was low. The genomic regions of OCU1, OCU8 and OCU13 revealed novel candidate genes. Further studies would be needed to validate the associations and explore their possible application in selection programmes. [ABSTRACT FROM AUTHOR]

Mucinous cystic neoplasms of the pancreas occur relatively frequently and mainly affect women in the transition to menopause. Most of these neoplasms are unique but are located in the body and tail of the pancreas and have no communication with the pancreatic ductal system. Less than 20% are malignant. Evaluation should include clinical presentation, imaging, endoscopic ultrasonography, puncture biopsies, cytology and chemical analysis of the liquid to measure angiotensin converting enzyme (ACE) levels. Complete surgical resection is the only treatment that can improve long-term survival in patients with malignant mucinous cystic lesions. This article includes a review of the literature related to presentation of a case diagnosed by the surgical clinical gastroenterology group at Clínica la Presentación in Manizales, Colombia. [ABSTRACT FROM AUTHOR]

Abstract: In this work we present an improvement on the normalized plane-wave method, for use in studies on carrier confinement in quantum dots. This alternative approach has two main advantages: it noticeably increases the accuracy of the calculations by removing the barrier surrounding the dot under study and it dramatically decreases the computation times. As we will demonstrate, this new approach is obtained from a simple analysis of the calculations. We use this algorithm to study hole confinement in spherical Si quantum dots, and from it we propose a correction to the Effective Mass approach to be used in Si quantum dot simulations. With this technique we obtained results comparable to those calculated by the Tight-Binding method but using less computational resources. [Copyright &y& Elsevier]

Abstract: In this work we present a fast and accurate genetic algorithm to determine the envelope functions and eigenenergies of the ground states of electrons and holes in low-dimensional complex semiconductor structures. We have developed the theoretical formalism of the algorithm in a general way in order to make it easy to include arbitrary nonparabolic and anisotropic band profiles in the calculations. From these results, calculation of the bandgaps of nanostructures can be carried out efficiently. Besides presenting and testing the algorithm, we calculate the ground state of electron and holes in two-dimensional quantum dot arrays, taking nonparabolicity and anisotropy into account. [Copyright &y& Elsevier]

Making use of Bethe Bloch's approximation, it find the specifie loss of protons energy in natural means (air and lead); through a law of scale it solves the same problem for heavy charged particles (muones, piones, deuterones and alpha particles) in this environment. This method simplifies the process traditionally used for calculating the transfer of energy of charged particles in any means. [ABSTRACT FROM AUTHOR]

It has developped six mathematicals models derivated of physical análisis who serve like tool for determinating the speed more probable that carry a car in the moment when it produces a road accident It has used basic concepts of Newton's mechanics for derivating the mathematical models. [ABSTRACT FROM AUTHOR]

Abstract: In this work we present a theoretical study of the quantization in a p-type FD/SOI device with confinement in the main crystalline directions. To carry out this study, we solved the Schrödinger effective mass equation, taking into consideration non-parabolicity, warping and degeneracy of the silicon valence band. We investigated the relative populations of the lowest subbands, and proposed a set of subbands for the efficient analysis of hole dynamics. We also evaluated the phonon and interface roughness scattering rates to provide a qualitative picture of how confinement direction influences those rates. [Copyright &y& Elsevier]

The photon absorption coefficient in the arrays of InAs quantum dots embedded in GaAs is investigated. The influence of size and shape of the quantum dots on the miniband structure is analyzed. A detailed study is carried out in order to understand the physics relating to the absorption. The influence on the absorption coefficient due to the difference of energies between the lowest minibands, the joint density of states and the features of the wavefunctions are investigated in order to shed light on the phenomenon and understand it. The existence of thresholds in the absorption coefficient in the far infrared region, related to the shape of the quantum dots, is finally revealed, thus demonstrating that it may be an element to use both in future applications and in characterization of the materials. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the physics of electronic states in cubic InAs quantum dot periodic nanostructures embedded in GaAs. This study aims to provide an understanding of the physics of these systems so that they may be used in technological applications. We have focused on the effect of dot densities and dot sizes on the material properties, evaluating the miniband structure of electron states coming from the bulk conduction band, and have calculated the intraband photon absorption coefficient for several light polarizations. Strain is included in this analysis in order to obtain the conduction band offset between the materials by solving the Pikus-Bir 8×8 k·p Hamiltonian. We offer a comparison with approaches used by previous authors and clarify their range of validity. Finally, we draw our conclusions and propose future technological applications for these periodic arrangements. [ABSTRACT FROM AUTHOR]

This work reports the design, manufacturing and numerical simulation approach of a 6-pixel (4.5 mm2/pixel) electroluminescent quantum dot light emitting device (QLED) based on CuInS2/ZnS quantum dots as an active layer. The QLED device was fabricated using a conventional multi-layer thin film deposition. In addition, the electrical I–V curves were measured for each pixel independently, observing how the fabrication process and layer thickness have an influence in the shape of the plot. This experimental device, enabled us to create a computational model for the QLED based on the Transfer Hamiltonian approach to calculate the current density J (mA cm−2), the band diagram of the system, and the accumulated charge distribution. Besides, it is worth highlighting that the simulator allows the possibility to study the influence of different parameters of the QLED structure like the junction capacitance between the distinct multilayer set. Specifically, we found that the Anode-HIL interface capacitance has a greater influence in the I–V curve. This junction capacitance plays an important role in the current density increase and the QLED turn-on value when a forward voltage is applied to the device. The simulation enabled that influence could be controlled by the selection of the optimal thickness and transport layers during the experimental fabrication process. This work is remarkable since it achieves to fit simulation and experiment results in an accurate way for electroluminescent QLED devices; particularly the simulation of the device current, which is critical when designing the automotive electronics to control these new nanotechnology lighting devices in the future. [ABSTRACT FROM AUTHOR]

A compact model has been employed in organic thin film transistors (OTFTs) to study the electrical characteristics of the contacts, which are formed between the organic layer and source/drain electrodes of the OTFT. The model shows the importance of interrelating different physical phenomena: charge injection, redox reactions at the interface, and charge drift in the organic semiconductor. The model reproduces and explains several features that have been reported for current-voltage curves, ID-VC, at the contacts of OTFTs. The ID-VC curves are extracted from the experimental output characteristics by two techniques. One technique uses a set of transistors with different channel lengths and a simultaneous extraction of the ID-VC curve and the mobility of carriers in the channel of the transistor. When a set of transistors with different channel lengths is not available, we propose an iterative method for the simultaneous extraction of the ID-VC curve and the mobility by changing the gate bias voltages. [ABSTRACT FROM AUTHOR]

This work proposes an analytical modelling of non-parabolicity for the valence bands of Si and Ge. With this aim, we obtained piecewise functions that enabled analytical evaluation of the energy after a free flight under drift, avoiding iterative procedures. In addition, particular attention was devoted to solving the problem of discontinuities in the density of states in bulk semiconductors, a shortcoming that had emerged in earlier approaches. Using our analytical functions, we were able to evaluate the mean hole energies at equilibrium and compare them with previous studies based on the pseudopotential method, obtaining an excellent agreement. We also used our analytical expressions in a single-particle Monte Carlo simulator to obtain the drift velocity under an external electric field and ohmic mobilities in pure Si and Ge. These results were compared with the experimental data and showed satisfactory agreement in all cases. [ABSTRACT FROM AUTHOR]

Injuries to the peripheral nerves represent a frequent cause of permanent disability in adults. The repair of large nerve lesions involves the use of autografts, but they have several inherent limitations. Overcoming these limitations, the use of decellularized nerve matrix has emerged as a promising treatment in tissue regenerative medicine. Here, we generate longer human decellularized nerve segments with a novel decellularization method, using nonionic, zwitterionic, and enzymatic incubations. Efficiency of decellularization was measured by DNA quantification and cell remnant analysis (myelin, S100, neurofilament). The evaluation of the extracellular matrix (collagen, laminin, and glycosaminoglycans) preservation was carried out by enzyme-linked immunosorbent assay (ELISA) or biochemical methods, along with histological and immunofluorescence analysis. Moreover, biomechanical properties and cytocompatibility were tested. Results showed that the decellularized nerves generated with this protocol have a concentration of DNA below the threshold of 50 ng/mg of dry tissue. Furthermore, myelin, S100, and MHCII proteins were absent, although some neurofilament remnants could be observed. Moreover, extracellular matrix proteins were well maintained, as well as the biomechanical properties, and the decellularized nerve matrix did not generate cytotoxicity. These results show that our method is effective for the generation of decellularized human nerve grafts. The generation of longer decellularized nerve segments would allow the understanding of the regenerative neurobiology after nerve injuries in both clinical assays and bigger animal models. Effective decellularization of human nerve matrix for regenerative medicine with a novel protocol. Combination of zwitterionic, non-ionic detergents, hyperosmotic solution and nuclease enzyme treatment remove cell remnants, maintain collagen, laminin and biomechanics without generating cytotoxic leachables. [ABSTRACT FROM AUTHOR]

Introduction: Idiopathic autoimmune hepatitis (IAH) is a chronic disease that occurs predominately in women, has episodic activity and remission, and favors hepatic fibrosis. Forty percent of patients have family histories of autoimmune diseases. It is apparently mediated by antigen-antibody interaction, but its causes are unknown. IAH is frequently associated with hepatobiliary cancer, less frequently with lymphomas, skin cancer and colon cancer and very rarely with hereditary colon cancer syndrome. This case debuted IAH and rectal bleeding caused by familial adenomatous polyposis (FAP) and adenocarcinoma of the sigmoid colon. Clinical case: The patient was a 51-year-old woman who had had IAH for one year which had been managed with prednisolone and azathioprine. A total colonoscopy, performed because of anemia, found multiple polyps that measured 5 and 10 mm and one ulcerated 30 mm sessile polyp in the sigmoid colon. A multiple endoscopic polypectomy revealed a tubulovillous adenoma with high and low grade dysplasia in several polyps and a low grade adenocarcinoma in the sigmoid polyp. Tests and examinations for metastasis were negative. Following presurgical nutritional repletion, a subtotal colectomy was performed and an ileal pouch-anal anastomosis with protective ileostomy was created. The pathology of the surgical specimen showed low grade adenocarcinoma of the colon and tubular and tubulovillous adenomas with high and low grade dysplasia. Discussion and conclusions: Association of IAH with familial adenomatous polyposis (FAP) and colorectal cancer (CC) occurs infrequently although associations of IAH with hepatobiliary cancer associated with cirrhosis, lymphomas, skin cancer and other autoimmune disorders are well-known. The prognosis is bad and no clear correlation with immune modulators can be established. [ABSTRACT FROM AUTHOR]

Anorectal endosonography can diagnose many diseases of the anal canal and rectum. In Colombia, the procedure is performed in only a few medical centers because of the scarcity of trained personnel. Four years ago, a group of teachers from the gastroenterological surgery clinical at the University of Caldas received training in endoluminal ultrasonography in Chile and Spain and have been practicing these procedures ever since. This is a descriptive study of a prospective cohort using data from patients who underwent endoluminal ultrasonography between October 2014 and September 2015. Data were obtained from 136 patients, of whom 72.05% were women. 20.6% of the patients came from departments other than Caldas. Fecal incontinence was the reason for the procedure for 44 patients (32.35%, 86% of whom were women). Other indications were rectal malignancies (23.5%), perianal fistulas (12.5%), anal pain (11.03%), endometriosis (7.35%), and perianal abscesses (6.62%). The most common final diagnoses were defective sphincters in 40 patients (29.41%), rectal malignancy in 13.24% of the patients, perianal fistulas in 11.76% of the patients, perianal abscesses in 8.82% of the patients, and benign rectal neoplasms in 6.62% of the patients . The results are consistent with those found in the international literature where the most common final diagnoses reported for the reason for fecal incontinence are sphincter defects and obstetric disorders. Anorectal endosonography is of great importance when used alone or to support other diagnostic tools. It is recommended that this procedure be done in a referral center such as ours which performs a large volume of these procedures and which follows international guidelines. [ABSTRACT FROM AUTHOR]