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Recycled concrete aggregates (RCAs) have been demonstrated as an alternative source to exhaustible natural aggregates. In this paper, we focus on the enhancement treatments for coarse and fine RCAs and the effect of these treatments on the durability of recycled concrete (RC) made from treated RCAs by the weakening and strengthening of the cement paste adhered to their surface. We conducted comparative analyses on the improvement of durability and mechanical properties. The results showed that the reduction of water absorption in RCAs increases the compressive strength of RC and that there is a strong linear trend of improvement in the carbonation depth, chloride ion penetration, and compressive strength of RC. For fine and coarse RCAs, the treatment mechanism and particle size are determinants in efficiently improving RC durability., El uso de áridos de hormigón reciclado (RCA) ha demostrado ser una fuente alternativa a los áridos naturales agotables. Este trabajo se centra en los tratamientos de mejora de los RCA, tanto gruesos como finos, y su efecto en la durabilidad del hormigón reciclado (RC) a partir de tratamientos por debilitamiento y fortalecimiento de la pasta de cemento adherida a su superficie de los RCA. Se llevaron a cabo análisis comparativos sobre la mejora de la durabilidad y las propiedades mecánicas, permitiendo identificar que la reducción de la absorción de agua de los RCA conduce a un aumento en la resistencia a la compresión del RC, y que existe una fuerte tendencia lineal de mejora de la profundidad de carbonatación, la penetración de iones cloruro y la resistencia a la compresión, donde el mecanismo de tratamiento y el tamaño de partícula son determinantes para lograr una mejora eficiente de la durabilidad del RC.

This research aims to improve the quality of recycled concrete fine aggregates (RFA) by using diammonium hydrogen phosphate (DAP). We aimed to understand the effect of DAP treatment on durability performance due to the carbonation action of mortars with the partial and total substitution of treated RFA. The results showed a maximum reduction in the RFA water absorption of up to 33% using a minimum DAP concentration due to a pore refinement as a consequence of the formation of calcium phosphates such as hydroxyapatite (HAP). The carbonation phenomenon did not have a significant effect on the durability of mortars with DAP-treated RFA, as we did not find a decrease in the compressive strength; the carbonation depth of the mortars with 100% treated RFA decreased up to 90% and 63% for a w/c of 0.45 and 0.50, in comparison with mortars with 0% treated RFA. An inversely proportional relationship was found between the accelerate carbonation and the compressive strength, showing that higher percentages of treated RFAs in the mortar promoted an increase in compressive strength and a decrease in the carbonation rate, which is behavior associated with a lower permeability of the cement matrix as one of the consequences of the microstructural densification by DAP treatment.

In this work we present a methodology based on the robust coloring problem (RCP) and the vertex cover problem (VCP) in order to find the communities in multiplex networks. For this, we consider that the RCP finds a partial detection based on the similarity of connected and unconnected nodes and using VCP we look for that number of groups (previously found) to be minimized. In order to apply this methodology, we present the characterization of the behavior and dynamics of employment in the Mexican population before and during the COVID-19 pandemic. This characterization is carried out with the use of four complex multiplex networks, where each node represents a federative entity (state) of the country and the intralayer relationships are given by the quantification of the generation and loss of jobs; while the interlayer connections are the replicas of each of the states, for each period. Specifically for this work, we contemplate the years 2018, 2019, 2020 and 2021.

Technological developments for improving the performance of conventional solar cells have become a topic of great interest in recent years. For instance, solar concentrators, new anti-reflective coatings, and Luminescent Down-Shifting Layers (LDS), among different techniques have been used in the past. The latter is an attractive option because an LDS layer has the property of increasing the photon flux density in the appropriate wavelength range on top of a cell device with the possibility of increasing the photo-current density. Then, in this work we focus on the development of a theoretical model to determine the cell´s illumination current density, considering the modified solar spectrum, and taking in account the modified spectral reflectance and transmittance at the upper layers when an optimized LDS layer is inserted on a solar cell. The correct selection of such a layer for a specific solar cell would increase its performance due to the enhanced photon density in the absorption region for which the solar cell has the highest quantum efficiency. As an example, it is shown that a Lu3Al5O12:Ce3+ layer on top of a CdTe solar cell might cause an efficiency increase of around 21%.

Currently, the obtention of nano-structures based on III-V materials is expensive. This calls for novel and inexpensive nanostructure manufacturing approaches. In this work we report on the manufacture of a nanostructures consisting of alternating layers of In and GaAs on a silicon substrate by magnetron sputtering. Furthermore, we characterized the produced nanostructures using secondary ion mass spectroscopy (SIMS), X-ray diffraction analysis, and Raman spectroscopy. SIMS revealed variation in the concentration of In atoms across In/GaAs/In interphases, and X-ray diffraction revealed planes corresponding to phases associated with GaAs and InAs due to In interfacial diffusion across GaAs layers. Finally, in order to study the composition and crystalquality of the manufactured nanostaructures, Raman spectra were taken using laser excitation lines of 452 nm, 532 nm, and 562 nm at different points across the nanostructures.This allowed to determine the transverse and longitudinal optical modes of GaAs and InAs,characteristic of a two-mode behavior. An acoustic longitudinal vibrational mode LA(Γ) of GaAs and an acoustic longitudinal mode activated by disorder (DALA) were observed. These resulted from the substitution of Ga atoms for In atoms in high concentrations due to the generation of Ga(VGa) and/or Arsenic(VAs) vacancies.This set of analyses show that magnetron sputtering can be aviable and relatively low-cost technique to obtain this type of semiconductors.

El estudio fue realizado con el propósito de identificar la micoflora asociada con la semilla de amaranto (Amarantus hypochondriacus L.) y determinar si Macrophoma sp. es transmitido por esta vía ya que en regiones productoras de amaranto se presenta en forma de epifitia y de manera enfítica y existe la evidencia de que el patógeno es transmitido por semilla. En semilla de amaranto proveniente de siembras comerciales cosechadas en 1995, en Tlaxcala, México, se evaluó la incidencia de los patógenos por el método del papel secante y congelamiento y, además, mediante el método del lavado se determinó la presencia de un carbón que ataca al ovario de la flor de esta especie, se identificó y cuantificó la densidad de inóculo por kilogramo de semilla. Los hongos de campo que se encontraron fueron: Alternaria spp., Fusarium lateritium, Fusarium sp., Phoma sp., Chaetophoma sp. y Peyronellaea sp. y como hongos de almacén Aspergillus spp. y Penicillium sp.; además, por primera vez se identificó en México a Thecaphora amaranthi (Hirschhorn) K. Vánky atacando las plantas de amaranto y transportado por la semilla, y en ésta no se encontró a Macrophoma sp.

An inherited gain-of–function variant (E756 del) in the mechanosensitive cationic channel PIEZO1 was recently shown to confer a significant protection against severe malaria. Here, we demonstrate in vitro that human red blood cell (RBC) infection by Plasmodium falciparum is prevented by the pharmacological activation of PIEZO1. The PIEZO1 activator Yoda1 inhibits RBC invasion, without affecting parasite intraerythrocytic growth, division or egress. RBC dehydration, echinocytosis and intracellular Na+/K+ imbalance are unrelated to the mechanism of protection. Inhibition of invasion is maintained, even after a prolonged wash out of Yoda1. Similarly, the chemically unrelated activators Jedi1 and Jedi2 potently inhibit parasitemia, further indicating a PIEZO1-dependent mechanism. Notably, Yoda1 treatment significantly reduced RBC surface receptors of P. falciparum, and decreased merozoite attachment and subsequent RBC deformation. Altogether these data indicate that the pharmacological activation of Piezo1 in human RBCs inhibits malaria infection by impairing P. falciparum invasion.

In the context of the COVID-19 pandemic, there is concern regarding the impact of the influenza season.To analyze the impact of influenza immunization history on patients with SARS-CoV-2 infection.Patients older than 18 years with COVID-19, registered between March and August 2020, were included. Data were analyzed using Fisher's exact test and Student's t-test. To evaluate the impact on mortality, a logistic regression model was used; the relationship between the percentage of patients who received the influenza vaccine and mortality was determined with Pearson's correlation coefficient.16,879 participants were included; 17 % had a history of influenza vaccination. Mortality was lower in the group with a history of vaccination (3.5 % vs. 7 %, p0.0001). The vaccination rate had an inverse relationship with the mortality rate (Pearson's r: -0.922, p = 0.026).Previous influenza immunization was an independent protective factor for mortality in patients with COVID-19. Although further studies are needed to determine a causal relationship, it would be reasonable to increase influenza immunization in the general population.En el contexto de la pandemia de COVID-19 existe inquietud en cuanto al impacto de la temporada de influenza.Analizar el impacto del antecedente de inmunización contra influenza en pacientes con infección por SARS-CoV-2.Se incluyeron pacientes mayores de 18 años con COVID-19, registrados entre marzo y agosto de 2020. Los datos fueron analizados mediante las pruebas exacta de Fisher y t de Student. Para evaluar el impacto en la mortalidad se utilizó un modelo de regresión logística; la relación entre el porcentaje de pacientes a quienes se aplicó la vacuna contra la influenza y la mortalidad fue determinada con el coeficiente de correlación de Pearson.Se incluyeron 16 879 participantes; 17 % tuvo antecedente de vacunación contra influenza. La mortalidad fue menor en el grupo con historia de vacunación (3.5 % versus 7 %, p0.0001). El porcentaje de vacunación presentó una relación inversa con el porcentaje de mortalidad (r de Pearson – 0.922, p = 0.026).La inmunización contra la influenza fue un factor protector independiente de mortalidad en pacientes con COVID-19. Aunque son necesarios más estudios para determinar la relación causal, será razonable incrementar la inmunización contra influenza en la población general.

One of the many effects of soft tissues under mechanical solicitation in the cellular damage produced by highly localized strain. Here, we study the response of peripheral stress fibers (SFs) to external stretch in mammalian cells, plated onto deformable micropatterned substrates. A local fluorescence analysis reveals that an adaptation response is observed at the vicinity of the focal adhesion sites (FAs) due to its mechanosensor function. The response depends on the type of mechanical stress, from a Maxwell-type material in compression to a complex scenario in extension, where a mechanotransduction and a self-healing process takes place in order to prevent the induced severing of the SF. A model is proposed to take into account the effect of the applied stretch on the mechanics of the SF, from which relevant parameters of the healing process are obtained. In contrast, the repair of the actin bundle occurs at the weak point of the SF and depends on the amount of applied strain. As a result, the SFs display strain-softening features due to the incorporation of new actin material into the bundle. In contrast, the response under compression shows a reorganization with a constant actin material suggesting a gliding process of the SFs by the myosin II motors.

Solar cells based on CuInGaSe2 (CIGS) have attained the highest record efficiency (22.9%) among thin film solar cells. CIGS is formed by the appropriate mixing of CuInSe2 (CIS) which has a bandgap around 1 eV and CuGaSe2 (CGS) which has a bandgap around 1.7 eV. These bandgaps are close to the optimal values for two-junction tandem solar cells. Therefore, CGS on CIGS or CGS on CIS tandem cells should be attractive and viable to achieve high efficiency and cost-effective thin film solar cells. In this work, a simple unified analytical model is used to design two-terminal and four-terminal CGS/CIGS tandem solar cells, establishing a realistic value for the expected efficiency in each case. Short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) and efficiency, are determined as a function of the CGS and CIGS acceptor impurity concentrations, back surface recombination velocities, minority carrier diffusion lengths, and absorber layer thickness. It is shown that realistic efficiencies over 30% can be achieved under one sun AM1.5 spectrum for both of the terminal configurations, but the optimum composition for the CIGS sub-cell should be different depending on the respective tandem cell configuration.

En el cultivo de amaranto (Amaranthus hypochondriacus L.) no se han realizado evaluaciones que aborden de manera simultánea la producción comercial de grano y su volumen de expansión en las variedades cultivadas en México. El objetivo del presente estudio fue evaluar el rendimiento, su estabilidad y expansión de grano, así como algunas características agronómicas de 10 variedades de amaranto en cinco localidades de los Valles Altos de Puebla. Se evaluaron siete variedades mejoradas: Nutrisol, Revancha, Laura, Gabriela, Diego, Areli y PQ2. Los testigos fueron dos poblaciones locales identificadas como C30 y C2, y la población del agricultor cooperante (CrPr) donde se estableció cada ensayo. Las evaluaciones en campo se hicieron en Tochimizolco, Tecuanipan, Calpan, Chiautzingo y Ciudad Serdán, en el estado de Puebla, México, utilizando un diseño experimental de bloques completos al azar con tres repeticiones en cada localidad. Las variables medidas fueron rendimiento de grano (REND), días a floración masculina, altura de planta, longitud de panoja, peso hectolítrico y peso de mil semillas. En reventado de grano se midió volumen de expansión (VEXP) y rendimiento de grano reventado. Se realizó análisis de varianza, prueba de medias y análisis de estabilidad para REND y VEXP mediante el modelo AMMI. El análisis de varianza mostró diferencias estadísticas significativas entre variedades y localidades en casi todas las variables; la interacción variedade × localidade fue significativa en seis de siete variables registradas. Las variedades sobresalientes en REND fueron C30, Laura, C2, CrPr y Nutrisol, con 3439, 3272, 3020, 2885 y 2847 kg ha-1, respectivamente. En VEXP, C2 fue la mejor variedad con 10.0 mL g-1. El análisis AMMI de REND mostró que las variedades más estables fueron Laura y Diego, mientras que en VEXP las más estables fueron Gabriela, Nutrisol y Laura. La mejor variedad mejorada fue Laura ya que presentó alto REND, aceptable VEXP y estabilidad en REND y VEXP.

Polycrystalline thin film solar cells made with absorber materials such as CdTe, CIGS, CZTS and metalorganic halides (perovskites) are currently important alternatives for the silicon solar cell technology, which still dominates the photovoltaic market. Then, it is important to have tools which can be used to design this kind of solar cells. For this purpose, we have developed a unified simple analytical model that can be applied to thin film solar cells. The model is based on the basic physics of hetero-junction devices, but it takes into consideration that the space charge region can extend along the major part of the cell length, particularly for very thin cells, causing important effects that typically are not observed in conventional junction devices. Photo-generated carriers are collected by electric field-drift instead of diffusion, and simultaneously strong recombination at this region may dominate the electrical I–V characteristic of the cell. Since the space-charge region width varies with the applied voltage, the illumination current density and the saturation dark current density are no longer independent of the voltage as is assumed for conventional solar cells. When the model is applied to CIS and CdTe solar cells as examples, it is found that it is possible to design very thin film solar cells (absorber less than 1 μm thick) with high efficiencies, whenever the recombination velocity at the back surface becomes small (102 cm/s), instead of the high recombination velocities present at ohmic contacts (107 cm/s). This fact implies the cost reduction of thin film solar cells by reducing absorber material thickness, and therefore it poses a challenge to develop deposition methods for very thin CdTe and CIGS absorber materials without pinholes, so that improved efficiencies are obtained when the surface recombination velocity is made small at the back by having a p+ or an electron blocking region before the ohmic contact. This result also explains the high efficiencies achieved by very thin perovskite solar cells.

RESUMEN Actualmente, la fabricación de películas delgadas de GaAs dopadas con Mn (GaAsMn) sobre Si (100), es un objeto de gran interés debido a su posible integración con la tecnología del silicio, generando un desarrollo significativo en la funcionalidad de los dispositivos optoelectrónicos y espintrónicos. En este trabajo, presentamos un estudio sistemático de la caracterización estructural, morfológica, óptica, y magnética de películas delgadas de GaAsMn preparadas por pulverización catódica R.F sobre un substrato de silicio (100), para temperaturas del crecimiento de 100 y 200 oC, respectivamente. A partir de los espectros Raman se identificaron los modos vibracionales, trasversal óptico (TO) y longitudinal óptico (LO) de GaAs, localizados en 290 cm-1 y 265 cm-1, respectivamente. Adicionalmente, se identificaron modos vibracionales de MnAs, debido a la substitucion de átomos de Ga por átomos de Mn en altas concentraciones. La segregación de Mn, fue corroborada mediante difracción de rayos-X, en donde se evidencian planos cristalinos en las direcciones (400) y (200) de GaAs policristalino, y planos cristalográficos pertenecientes a fases de Mn1+xAs. La morfología y el modo de crecimiento de las películas delgadas de GaAsMn/Si (100), se llevó a cabo mediante imágenes de microscopía de fuerza atómica (AFM) y microscopía electrónica de barrido (SEM) tomadas sobre la superficie y en sección transversal, respectivamente. Finalmente, un análisis de las propiedades magnéticas de las películas delgadas de GaAsMn a partir de imágenes de microscopía de fuerza magnética (MFM), revelan la presencia de dominios magnéticos superficiales provenientes de MnAs. Concluimos que las propiedades físicas de las películas de GaAsMn dependen de las condiciones de crecimiento. ABSTRACT Currently, the manufacture of thin films of GaAs doped with Mn (GaAsMn) on Si (100), is an object of great interest, due to its possible integration with silicon technology, generating a significant development in the functionality of the devices optoelectronics and spintronics. In this work, we present a systematic study of the structural, optical, morphological and magnetic characterization of GaAsMn thin films prepared by R.F sputtering on a Si (100) substrate, for growth temperatures of 100 and 200 oC, respectively. From Raman spectra, the transverse optical (TO) and longitudinal optical (LO) vibrational modes, located at 290 cm-1 and 265 cm-1 of GaAs were identified. Additionally, vibrational modes of MnAs were identified, due to the replacement of Ga atoms with Mn atoms in high concentrations. The segregation of Mn was bear out by X-ray diffraction, where crystalline planes are evidenced in the directions (400) and (200) of polycrystalline GaAs, and crystallographic planes belonging to the Mn1+xAs phases. The morphology and growth mode of the thin films of GaAsMn / Si (100), was carried out by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM) images, taken on the surface and in cross-section, respectively. Finally, an analysis of the magnetic properties of the GaAs thin films made from magnetic force microscopy (MFM) images, evidence surface magnetic domains formation, which depending on growth conditions. We concluded that, all properties of GaAsMn thin films are depending on growth conditions.

Solar cells based on silicon dominate the current market, but its single junction conversion efficiency will never exceed 30%. However, it is possible to surpass this limit by coupling silicon solar cells with III-V multi-junction solar cells; for example, a combination of materials such as InGaP/GaAs or AlGaAs/GaAs on a silicon-based solar cell. In this work, by using a simple model, developed before, the efficiencies of InGaP/GaAs/Si- HJ solar cells with two and four-terminals are calculated. As expected, the four-terminals configuration would provide the highest efficiency since the bandgaps of the involved semiconductors are not optimum for a two-terminals configuration. The expected practical efficiencies at 1 sun (AM1.5 spectrum) for a four-terminals tandem cell can be as high as 41.7%, when the appropriate thickness for each layer, including the anti- reflection coating, are used. In the case of Al 2 O 3 as ARC, the optimum thickness is 88 nm, while the optimum InGaP thickness is 260 nm and GaAs optimum thickness is 1100 nm. The results shown here can be compared with the experimental efficiency around 35.9%, achieved recently for this kind of solar cells. Therefore, triple junction InGaP/GaAs//Silicon tandem solar cells continue being very attractive for further development, using high efficiency HIT silicon cell as the bottom sub-cell.

Perovskite solar cells (PSC) have been in development for a few years only, and quickly they have achieved high record efficiencies, above 23%, attracting great attention as a possible alternative to commercial Si solar cells. However, very few articles have dealt with the optical losses in this type of solar cells, but an important factor to be taken in account for developing highly efficient extra-thin solar cells, such as Perovskite Solar Cells, is the optical reflectance in the solar spectrum wavelength range for these devices. Reducing optical losses should cause improved photocurrent density and efficiency of the cell. Therefore, estimating the reflectance for each wavelength of the solar spectrum and the total average reflectance should help better design this kind of devices. Then, in this work we do calculations for planar multilayer perovskite solar cells using the Optical Matrix method for determining the expected reflectance as a function of wavelength, using refraction index and extinction coefficients for each of the materials that constitute the solar cells. Our results show that for very thin perovskite absorbers (less than 350 nm), the optical losses can become very high. Even for a typical perovskite thickness above 400 nm, the total average reflectance in the solar spectrum wavelength range can be as high as 10%, approximately. Then, in the future, a further increase of efficiency might be achieved by appropriate roughening of the perovskite layer surfaces.

Perovskite solar cells (PSC) have been under development for a few years only, and quickly they have achieved high record efficiencies, above 25 %, attracting great attention as a possible alternative to commercial Si solar cells. However, very few articles have dealt with the optical losses in this type of solar cells, but an important factor to be taken in account for developing highly efficient extra-thin solar cells, such as Perovskite Solar Cells, is the optical reflectance in the solar spectrum for these devices. Then, in this work, we do calculations for planar multilayer perovskite solar cells using the Optical Matrix method for determining the expected reflectance as a function of wavelength, using refraction index and extinction coefficients for each of the materials that typically constitute these solar cells. Our results show that for very thin perovskite absorber layers (less than 350 nm), the optical losses can become very high. Even for a typical perovskite thickness above 450 nm, the total average reflectance in the solar spectrum can be as high as 10 %, approximately.

Axonal beading—formation of a series of swellings along the axon—and retraction are commonly observed shape transformations that precede axonal atrophy in Alzheimer’s, Parkinson, and other neurodegenerative conditions. The mechanisms driving these morphological transformations are poorly understood. Here we report controlled experiments which can induce either beading or retraction and follow the time evolution of these responses. By making quantitative analysis of the shape modes under different conditions, measurement of membrane tension, and using theoretical considerations, we argue that membrane tension is the main driving force that pushes cytosol out of the axon when microtubules are degraded, causing axonal thinning. Under pharmacological perturbation, atrophy is always retrograde and this is set by a gradient in the microtubule stability. The nature of microtubule depolymerization dictates the type of shape transformation vis à vis beading or retraction. Elucidating the mechanisms of these shape transformations will facilitate development of strategies to prevent or arrest axonal atrophy due to neurodegenerative conditions.

Polar growth is a fundamental mode of cell morphogenesis observed in nearly all major groups of organisms. Among polarly growing cells, the angiosperm pollen tubes have emerged as powerful experimental systems in large part because of their oscillatory growth, which provides a window into the network of interactions regulating morphogenesis. Empirical studies of oscillatory pollen tubes have sought to uncover the temporal sequence of cellular and molecular events that constitutes an oscillatory cycle. Here we show that in lily pollen tubes the distance or wavelength (λ = 6.3 ± 1.7 μm) over which an oscillatory cycle unfolds is more robust than the period of oscillation (τ = 39.1 ± 17.6 s) (n = 159 cells). Moreover, the oscillatory cycle is divided into slow and fast phases, with each phase unfolding over precisely one half of the wavelength. Using these observations, we show that a simple spatial bi-oscillator predicts the most common modes of oscillation observed in pollen tubes. These results call into question the traditional view of pollen tube morphogenesis as a temporal succession of cellular events. Space, not time, may be the most natural metric to inteprete the morphogenetic dynamics of these cells.

Multi-junction solar cells (SC) made from III–V compound semiconductors are still in the development phase. Here, we perform calculations for multi-junction cells: AlxGa1−xAs top junction, GaAs middle junction and InyGa1−yAs bottom junction (all of these materials with band-gaps between 2.1 and 0.8 eV) in order to obtain the optimal band gap and thickness for each junction under the AM1.5 solar radiation spectrum. The ideal photo-current density is around 15.5 mA/cm2. In order to reduce the natural reflectivity, an anti-reflective coating (ARC) was chosen, based on a MgF2/ZnS double layer, allowing for a significant increase of the current density with respect to a cell without it. Calculations of external quantum efficiency (QE) were also performed for the three cases mentioned above: ideal one, taking into account the total reflection and with the ARC double layer. Finally, when more realistic calculations are done, taking into account the carrier recombination at each sub-cell, and the light reflection for a tandem cell with the designed ARC on top, the expected conversion efficiency (η), under the AM 1.5 spectrum (without concentration), was determined to be around 38.5%, making this an attractive III–V compound tandem cell to be investigated in the near future.

The problem of stabilizing the spreading process to a prescribed probability distribution over a complex network is considered, where the dynamics of the nodes in the network is given by discrete-time Markov-chain processes. Conditions for the positioning and identification of actuators and sensors are provided, and sufficient conditions for the exponential stability of the desired distribution are derived. Simulations results for a network of N = 10 6 corroborate our theoretical findings.

In this work the control design problem for the Schrödinger equation with an arbitrary potential is addressed. In particular a controller is designed which (i) for a space-dependent potential steers the state probability density function to a prescribed solution and (ii) for a space and state-dependent potential exponentially stabilizes the zero solution. The problem is addressed using a backstepping controller that steers to zero the deviation between the initial probability wave function and the target probability wave function. The exponential convergence property is rigorously established and the convergence behavior is illustrated using numerical simulations for the Morse and the Pöschl-Teller potentials as well as the semilinear Schrödinger equation with cubic potential.

GaAs/In bilayers were prepared by RF Magnetron Sputtering in an Ar atmosphere on Si (100) substrates using high purity (95.95%) GaAs (100) and In targets. The growth temperatures were 300oC and 580oC for the high purity targets of In and GaAs, respectively. Three samples were prepared: the deposition time (td) for the GaAs layers was fixed to 30 minutes, while varied for the In layers from td = 10, 15, and 20 minutes. The morphological and optical studies of the samples were made by means of Amplitude Modulation Atomic Force Microscopy (AM-AFM). In order to analyze and correlate surface morphology and alloy composition properties, the as-prepared samples were cleaved along the [001] direction and subsequently studied by AM-AFM-micrographs. From topographic images, a statistical study of the roughness and grain size was made. Additionally, cross sectional AM-AFM-micrographs were performed for each sample, where the phase channel, which is sensitive to the material properties of the specimen, was of particular interest.