Simultaneous Extraction of Density of States Width, Carrier Mobility and Injection Barriers in Organic Semiconductors

The predictive accuracy of state–of–the–art continuum models for charge transport in organic semiconductors is highly dependent on the accurate tuning of a set of parameters whose values cannot be effectively estimated either by direct measurements or by first principles. Fitting the complete set of model parameters at once to experimental data requires to set up extremely complex multi–objective optimization problems whose solution is, on the one hand, overwhelmingly computationally expensive and, on the other, it provides no guarantee of the physical soundness of the value obtained for each individual parameter. In the present study we present a step–by–step procedure that enables to determine the most relevant model parameters, namely the density of states width, the carrier mobility and the injection barrier height, by fitting experimental data from a sequence of relatively simple and inexpensive measurements to suitably devised numerical simulations. At each step of the proposed procedure only one parameter value is sought for, thus highly simplifying the numerical fitting and enhancing its robustness, reliability and accuracy. As a case study we consider a prototypical n-type organic polymer. A very satisfactory fitting of experimental measurements is obtained, and physically meaningful values for the aforementioned parameters are extracted

Computation of Electrostatic Field near Three-Dimensional Corners and Edges

Theoretically, the electric field becomes infinite at corners of two and three dimensions and edges of three dimensions. Conventional finite-element and boundary element methods do not yield satisfactory results at close proximity to these singular locations. In this paper, we describe the application of a fast and accurate BEM solver (which usesexact analytic expressions to compute the effect of source distributions on flatsurfaces) to compute the electric field near three-dimensional corners and edges. Results have been obtained for distances as close as 1$\mu m$ near the corner/edge and good agreement has been observed between the present results and existing analytical solutions.Comment: Presented in International Conference on Computational and Experimental Engineering and Sciences held at IIT Madras, Chennai, India, during 1-6 December, 200

Injection Length in Staggered Organic Thin Film Transistors: Assessment and Implications for Device Downscaling

In staggered thin film transistors, the injection length is the fraction of the gate to contact overlap that is effectively involved in current injection. Its assessment is important to properly downscale device dimensions. In fact, in order to increase transistor operation speed, the whole device footprint should be downscaled, which means both the gate to contact overlap and the channel length, as they affect the relative weight of gate to contact parasitic capacitances and the carrier transit time along the channel respectively. Nevertheless, it is not advisable to make the gate to contact overlap smaller than the injection length, because this negatively affects contact resistances. Suitable figures of merits are introduced to quantify these aspects, and a method is proposed to extract the injection length from electrical measurements. As an example of application, transistors based on the prototypical n-type polymer poly[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene) (P(NDI2OD-T2) are analyzed. When the channel length is scaled while driving voltages are kept constant, in P(NDI2OD-T2) the injection length decreases as well, thus proving that the downscaling of the whole device footprint is feasible. The physical origins of this finding are analyzed and traced back to material properties, in order to suggest general guidelines for a successful transistor downscaling

Análisis prospectivo estratégico de la educación superior en Colombia

Las universidades deben adaptarse y anticipar los desafíos emergentes para mantener su papel en la sociedad. Este artículo tiene como objetivo proponer un marco de prospectiva educativa que facilite el análisis de los futuros alternativos en las instituciones de educación superior. Se utiliza una metodología prospectiva de tipo normativa, se aplican entrevistas semi-estructuradas a expertos, como base para un análisis morfológico que oriente la definición de escenarios futuros. Los resultados permiten caracterizar el panorama estratégico de la educación superior en Colombia y se identifican las variables de mayor influencia en los procesos de acreditación institucional; específicamente se analiza el caso de la Institución Universitaria Escuela Nacional del Deporte (Valle del Cauca, Colombia). Se formulan los escenarios de futuro inercial, desarrollo incremental, cambio estructural y retroceso, que conllevan a la elaboración de recomendaciones estratégicas para el escenario apuesta. Se concluye que el análisis de prospectiva educativa propuesto integra aspectos institucionales, de internacionalización, ciencia, tecnología e innovación y proyección social para la construcción de escenarios alternativos de futuro útiles para la toma de decisiones estratégicas en las instituciones de educación superior.Universities must adapt and anticipate emerging challenges to maintain their role in society. This article aims to propose an educational prospective framework that facilitates the analysis of alternative futures in higher education institutions. A normative prospective methodology is used, semi-structured interviews with experts are applied, as the basis for a morphological analysis that guides the definition of future scenarios. The results allow characterizing the strategic panorama of higher education in Colombia and the variables with the greatest influence on institutional accreditation processes are identified; specifically, the case of the University Institution of the National Sports School (Valle del Cauca, Colombia) is analyzed. The scenarios of inertial future, incremental development, structural change and setback are formulated, which lead to the elaboration of strategic recommendations for the best scenario. It is concluded that the proposed educational prospective analysis integrates institutional, internationalization, science, technology and innovation aspects and social projection for the construction of alternative future scenarios useful for strategic decision-making in higher education institutions

Generadores e impulsores del marketing boca a boca en un programa de educación superior

At present, the use of traditional means of promotion and marketing has not turned out to be very effective for higher education institutions because the expected effects are not evident. Consequently, this article aims to identify the generators and drivers of word of mouth marketing in a higher education program. To carry out the research, a quantitative methodology was used, through stratified probabilistic sampling where 185 surveys were applied to students of the Business Administration program of the National School of Sports University Institution (Cali, Colombia). The results obtained show that students are the main generators of word of mouth, and that the greatest driver lies in the differentiating aspect of the academic program and the reputation of the institution.En la actualidad, el uso de medios tradicionales de promoción y marketing no ha resultado ser muy efectivo para las instituciones de educación superior por cuanto no se evidencian los efectos esperados. Consecuentemente, el presente artículo tiene como objetivo identificar los generadores e impulsores del marketing boca a boca a boca en un programa de educación superior. Para la realización de la investigación se empleó una metodología cuantitativa, a través de un muestreo probabilístico estratificado donde se aplicaron 185 encuestas a estudiantes del programa de Administración de Empresas de la Institución Universitaria Escuela Nacional del Deporte (Cali, Colombia). Los resultados obtenidos muestran que los estudiantes son los principales generadores del boca a boca, y que el mayor impulsor radica en el aspecto diferenciador del programa académico y la reputación de la institución

Generadores e impulsores del marketing boca a boca en un programa de educación superior

At present, the use of traditional means of promotion and marketing has not turned out to be very effective for higher education institutions because the expected effects are not evident. Consequently, this article aims to identify the generators and drivers of word of mouth marketing in a higher education program. To carry out the research, a quantitative methodology was used, through stratified probabilistic sampling where 185 surveys were applied to students of the Business Administration program of the National School of Sports University Institution (Cali, Colombia). The results obtained show that students are the main generators of word of mouth, and that the greatest driver lies in the differentiating aspect of the academic program and the reputation of the institution.En la actualidad, el uso de medios tradicionales de promoción y marketing no ha resultado ser muy efectivo para las instituciones de educación superior por cuanto no se evidencian los efectos esperados. Consecuentemente, el presente artículo tiene como objetivo identificar los generadores e impulsores del marketing boca a boca a boca en un programa de educación superior. Para la realización de la investigación se empleó una metodología cuantitativa, a través de un muestreo probabilístico estratificado donde se aplicaron 185 encuestas a estudiantes del programa de Administración de Empresas de la Institución Universitaria Escuela Nacional del Deporte (Cali, Colombia). Los resultados obtenidos muestran que los estudiantes son los principales generadores del boca a boca, y que el mayor impulsor radica en el aspecto diferenciador del programa académico y la reputación de la institución

Recombinant Anti-Human Melanoma Antibodies Are Versatile Molecules

The low cost, high versatility, and reliable production of bacterially produced recombinant antibody fragments speeds up the development of tumor-targeting agents. High-quality recombinant anti-melanoma antibodies are much sought after in the scientific community. We cloned the murine antibody 225.28S, currently used in radioimmunoimaging of human melanoma lesions, in single-chain Fv configuration (scFv) for soluble expression in bacteria. The recombinant antibody fragment conserved the binding specificity of the parental antibody. In order to arm the scFv(225.28S) with biologically useful effector functions, we developed vectors for soluble expression of scFv(225.28S) in bacteria that allow both covalent and noncovalent chemical antibody modification at positions that do not interfere with antigen binding. An expression vector was developed that appends a cysteine residue at the C-terminal extremity of the recombinant antibody, thus allowing reaction with thiol-specific reagents, including 99mTc labeling, at a position that does not interfere with antigen binding. The scFv(225.28S) was also successfully expressed with a casein kinase II substrate tag that enables efficient and stable 32P labeling. For noncovalent antibody modification, we developed an expression vector that appends the human calmodulin gene at the C-terminal extremity of scFv(225.28S). The calmodulin domain is poorly immunogenic and can be targeted with chemically modified high-affinity calmodulin ligands. The recombinant anti-human melanoma antibodies described in this article should prove useful “building blocks” for the development of anti-melanoma diagnostic and therapeutic strategies

Wireless tissue palpation: Head characterization to improve tumor detection in soft tissue

For surgeons performing open procedures, the sense of touch is a valuable tool to directly access buried structures and organs, to identify their margins, detect tumors, and prevent undesired cuts. Minimally invasive surgical procedures provide great benefits for patients; however, they hinder the surgeon's ability to directly manipulate the tissue. In our previous work, we developed a Wireless Palpation Probe (WPP) to restore tissue palpation in Minimally Invasive Surgery (MIS) by creating a real-time stiffness distribution map of the target tissue. The WPP takes advantage of a field-based magnetic localization algorithm to measure its position, orientation, and tissue indentation depth, in addition to a barometric sensor measuring indentation tissue pressure. However, deformations of both the tissue and the silicone material used to cover the pressure sensors introduce detrimental nonlinearities in sensor measurements. In this work, we calibrated and characterized different diameter WPP heads with a new design allowing exchangeability and disposability of the probe head. Benchtop trials showed that this method can effectively reduce error in sensor pressure measurements up to 5% with respect to the reference sensor. Furthermore, we studied the effect of the head diameter on the device's spatial resolution in detecting tumor simulators embedded into silicone phantoms. Overall, the results showed a tumor detection rate over 90%, independent of the head diameter, when an indentation depth of 5 mm is applied on the tissue simulator