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The Hf/Ti ratio was precisely controlled at monolayer thickness using atomic partial layer deposition (APLD). HfxTi1−xO2 films with varying Hf concentrations were deposited by adjusting the pulse time of Hf precursors within a single atomic layer. Characterization using x-ray reflectivity, x-ray photoelectron spectroscopy, and spectroscopic ellipsometry confirmed the presence of Hf, Ti, and O in the films. Increasing the Hf content caused the binding energies of the O 1s peak to shift to higher values, indicating a chemical environment change from TiO2-like to HfO2-like. A higher Hf content also increased the relative atomic percentages of Hf, Ti, and O, altering the film properties. The mass density and optical properties were notably sensitive to changes in the Hf/Ti ratio at monolayer thickness. The potential of APLD to reduce dimensionality through precise control of both thickness and composition renders it especially appropriate for applications requiring highly specific material properties. [ABSTRACT FROM AUTHOR]

Complex morphology is observed in the GaAs:Bi cap layer of Ga(As,Bi) films grown on GaAs(001) substrates by low-temperature (LT) molecular beam epitaxy (MBE). The microstructure is dominated by the presence of V-shaped domains in the LT-GaAs cap layer and by the (unintentional) inhomogeneous incorporation of Bi from the underlying Ga(As,Bi) layer growth. Aberration-corrected scanning transmission electron microscopy techniques enabled two types of domain to be identified: (i) twinned domains and (ii) Bi-rich atomically ordered domains with triple periodicity. The observed microstructure is discussed in the context of LT-MBE growth in combination with the presence of a small amount of Bi, which seemingly alters adatom diffusivity. Surface processes and (surface) kinetic factors play a key role in the resultant morphology and explain the appearance of both types of domains. [ABSTRACT FROM AUTHOR]

A novel growth technique, called atomic partial layer deposition (APLD), has been proposed to expand the applications of, and the research in, atomic layer deposition (ALD). This technique allows the possibility for the fabrication of well-controlled alloys on a single atomic layer scale. To demonstrate the capabilities of this technique, samples of HfO2 and TiO2 were prepared as conventional ALD nanolaminates through the repeated exposure of the separated metal-precursor and reactant. Subsequently, HfO2-TiO2 APLD growth mode samples were obtained by varying the precursor doses and exposure times to obtain a fractional coverage in the monolayer of Hf and Ti. The thickness and structure of the samples were studied by X-ray reflectivity. The surface topography was studied using atomic force microscopy along with Kelvin probe force microscopy for surface potential mapping. Clear differences on the surface, compared with the conventional HfO2/TiO2 ALD nanolaminates, were observed, which confirmed the HfO2-TiO2 APLD growth. The films were analyzed using X-ray photoelectron spectroscopy (XPS) depth profile scans and angle resolved XPS, where well-defined HfO2 and TiO2 contributions were found for both the conventional and APLD mode samples, and an additional contribution, assigned to a ternary phase Hf-Ti-O, in the APLD grown films was observed. This result confirms that Hf and Ti form an alloy in a monolayer by APLD mode growth. [ABSTRACT FROM AUTHOR]

New H-mode regimes with high confinement, low core impurity accumulation, and small edge-localized mode perturbations have been obtained in magnetically confined plasmas at the Joint European Torus tokamak. Such regimes are achieved by means of optimized particle fueling conditions at high input power, current, and magnetic field, which lead to a self-organized state with a strong increase in rotation and ion temperature and a decrease in the edge density. An interplay between core and edge plasma regions leads to reduced turbulence levels and outward impurity convection. These results pave the way to an attractive alternative to the standard plasmas considered for fusion energy generation in a tokamak with a metallic wall environment such as the ones expected in ITER. [ABSTRACT FROM AUTHOR]

Since hydration heat generated during construction has been the cause of cracking and deformations in mass concrete structures, selecting appropriate thermal control plans is crucial in mass concrete construction. However, developing numerical models to predict the heat of hydration in mass concrete involves complex processes that demand extensive knowledge in thermodynamics and related fields, which can result in increased costs and extended timelines for construction methods and material selection. To address this problem, this research aims to develop a simple decision-making framework to select a cost-effective thermal control method using nomograms for materials and construction engineers. Several nomograms, including temperature and cost nomograms, were used to provide the most cost-effective thermal control plans while satisfying the maximum temperature limits of mass concrete. A case study of an actual construction project was used to validate and demonstrate the proposed framework. The effectiveness of this framework was demonstrated through a case study on a real construction project, which validated the approach and confirmed its potential to reduce the time required for developing thermal control plans in mass concrete construction projects. The findings from this study highlight the proposed framework's capability to streamline the thermal control method selection process, thereby facilitating a more intuitive understanding of thermal control options and markedly reducing both costs and time in mass concrete construction projects. [ABSTRACT FROM AUTHOR]

We report on the spontaneous formation of lateral composition modulations (LCMs) in Ga(As,Bi) epilayers grown by low-temperature (<300 °C) molecular beam epitaxy (MBE) on GaAs(001). Both cross-section and plan-view transmission electron microscopy techniques are used to investigate the nature of the LCMs, consisting of Bi-rich cylinder-like nanostructures lying along the [001] growth direction. The observed LCMs are the consequence of a two-dimensional phase separation process occurring at the surface of the growing epilayers, and their columnar nature is consistent with a surface-directed spinodal decomposition process. Although LCMs are thermodynamically driven, we show how they can be kinetically controlled, in particular, through the As/Ga flux ratio and the substrate temperature. This is a result of LCMs developing from surface atomic diffusion processes, since the atomic dimer configurations on the surface alter adatom diffusivity. The significant role of the surface reconstructions is also discussed. [ABSTRACT FROM AUTHOR]

Considering, as a limit case, an approximately flat pion distribution amplitude, which is determined from the hardest, in momentum space, solution of the Bethe–Salpeter equation for the pion wave function, we compute the pion transition form factor and the pion form factor Fπ(Q2), taking into account the LO as well as NLO form of the hard coefficient function entering the leading-twist factorization formula. We also compute the exclusive photoproduction of pions pairs at high energies, , where perturbative QCD can be used to compute the hard scattering matrix elements. We verify that the existent data for exclusive pion production can be reasonably described as a function of such a flat distribution amplitude. [ABSTRACT FROM AUTHOR]

In this work we show clear evidences that silicon segregation out of quantum wells (QWs) is the mechanism responsible for the unexpected photovoltaic (PV) effect exhibited by AlGaAs/AlAs/GaAs double-barrier quantum-well infrared photodetectors. Our results are based on the combined analysis of the detectors’ microstructure [obtained by transmission electron microscopy (TEM)] and their electro-optical characteristics (dark current and responsivity versus bias). A TEM image intensity analysis yields the result of an unintentional asymmetry between the two AlAs barriers adjacent to the QW attributed to the presence of segregated Si at the interface. Moreover, we find that the higher this compositional asymmetry, the higher the asymmetries in the electro-optical response of the detector. Additionally we show here direct evidences of how the growth-induced nonequivalence of the AlAs tunnel barriers can be ruled out as the origin of the PV effect. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present the advances in the implementation of the Smart Grids (SGs) in the whole world span and the prospectus of Colombia towards the implementation of new solutions. Mainly considering those technological developments and advances made in the electrical networks, related with the use of software for their analysis and management in different scenarios, to optimize the electrical system management and operation upon the new challenges that we have currently. For this matter, first is presented the theoretical framework which the SGs are focused and the advances in recent years, analyzing the metering, communication, security and control systems in comparison with future projected solutions. Subsequently, it is collected the general information about the actual projects that use solutions, as ETAP Real Time, which involves SGs implementation. At the same time, pointing out the advantages and disadvantages that the diverse implemented solutions possess, highlighting the technical and technological gaps regarding the consulted theory and the current state-of-the-art. Finally, the ETAP Real Time solution is presented as an integral alternative to help resolve the worldwide and Colombia implementation challenge of SGs. [ABSTRACT FROM AUTHOR]

We have determined the interface profiles of GaAs/Al0.25Ga0.75As and GaAs/AlAs terahertz quantum-cascade laser structures using transmission electron microscopy (TEM). The experimental composition profiles are directly extracted from the analysis of the diffracted intensity distribution of g002 dark-field TEM images. Simulated composition profiles, which have been obtained using a Fourier-transform-based model, are in remarkably good agreement with the experimental results so that the determined interface parameter can be used for designing terahertz quantum-cascade lasers. Due to the interface grading, these actual profiles reveal a significantly lower aluminum content of the Al0.25Ga0.75As and AlAs barriers than the nominal values. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum f. sp. vanillae is considered the most important fungus affecting vanilla crops around the world, causing rot on vanilla roots and stems. Previous studies showed that the ability to infect vanilla plants is a polyphyletic trait among strains of the Fusarium oxysporum species complex (FOSC). The same studies proposed a single origin for F. oxysporum f. sp. vanillae isolates sampled from Mexico, the centre of origin and distribution of vanilla. The aim of this work was to test the hypothesis of the monophyletic origin of a wider sample of isolates of F. oxysporum f. sp. vanillae infecting Mexican vanilla and estimate nucleotide diversity of pathogen isolates from the main vanilla‐producing countries. Sequence data for the TEF1α gene from 106 isolates was assembled. The phylogenetic analyses suggest that some Mexican isolates of F. oxysporum f. sp. vanillae belong in two well‐supported clades, mixed with isolates from Madagascar, Indonesia, Réunion and Comoros. The phylogenetic position of other Indonesian and Mexican isolates is unresolved. Estimations of nucleotide diversity showed that the population from Mexico is genetically more diverse than the other three populations from Madagascar, Indonesia and Réunion. The results support a polyphyletic origin of vanilla‐infecting isolates of F. oxysporum worldwide, and also reject the proposition that Mexican isolates have a single origin. The phylogenetic optimizations over the strict consensus tree of the ability to infect vanilla plants suggest that pathogenic strains around the world are the product of multiple shifts of pathogenesis and dispersion events. [ABSTRACT FROM AUTHOR]

Using transmission electron microscopy, we present an in-depth microstructural analysis of a series of Ga(Sb,Bi) epilayers and Ga(Sb,Bi)/GaSb quantum wells grown on GaSb(001) substrates by molecular beam epitaxy. Despite the dilute bismide compound Ga(Sb,Bi) is regarded as a highly-mismatched alloy, we find that the material is of remarkable structural perfection, even up to 11%–14% Bi, the maximum Bi concentration incorporated into GaSb so far. No extended defects, nanoclusters, or composition modulations are detectable in the pseudomorphic layers. In addition, the quantum wells exhibit regular and homogeneous morphologies including smooth and stable interfaces with a chemical width on the same order as in other high-quality III–V heterointerfaces. These results may give reasons for the recent successful realization of mid-infrared lasers with room temperature operation based on the very same quantum well structures. [ABSTRACT FROM AUTHOR]

This study presents an analysis of the photocatalytic efficiency in $$\hbox {TiO}_{2}$$ :N thin films grown by atomic layer deposition related to the film thickness. The nitriding process was carried out with nitrogen plasma by molecular nitrogen decomposition after $$\hbox {TiO}_{2}$$ deposition. The study was performed using the time-dependent degradation of colour units for methylene-blue solutions and inactivation percentages for Escherichia coli bacteria, for potential applications in sewage purification. To determine the optoelectronic properties of the films, the optical, structural, surface and thickness characterizations were carried out by photoluminescence, Raman spectroscopy, atomic force microscopy and scanning electron microscopy, respectively. [ABSTRACT FROM AUTHOR]

The microstructure and the element distribution across tensile-strained nitrogen δ-doped GaAs/(Al,Ga)As quantum wells (QW) are investigated by transmission electron microscopy. We find that the nitrogen sub-monolayer insertion results in a several monolayer thick Ga(As,N) layer with thickness and lateral composition fluctuations. The thickness and composition fluctuations are not arbitrary, but they are anticorrelated, i.e., the Ga(As,N) layer is thinner in areas of higher nitrogen content and vice versa. Thus, regardless of the specific position along the QW, the amount of incorporated nitrogen remains constant and close to its nominal value. The increase in the nitrogen content at the insertion promotes an anisotropic shape transition towards highly faceted three-dimensional structures. Our experimental observations indicate that the two-dimensional to three-dimensional morphological transition is determined by intrinsic factors associated with the different Ga-N and Ga-As bonds and hence occurs regardless of the epitaxial strain state of the layers. [ABSTRACT FROM AUTHOR]

Saline wetlands have received limited attention from researchers and this neglect has often resulted in their degradation and limited conservation, and insufficient information to design conservation and management plans. Gallocanta Lake is a nature reserve of international importance for winter birds. The importance of the soil here, which supports niches and protected habitats for certain species of birds, has been recognized more recently. The soil of Gallocanta Lake undergoes strong oscillations of saturation and drainage followed by drying because of irregular rain and variable flooding conditions associated with fluctuations in the level of the lake. This study examined reducing conditions and morphological indicators of reduction in the soil around the lake with indicators of reduction in soils ( IRIS) tubes, which are coated with iron oxides. We surveyed five sites for between 22 and 34 weeks. The average amount of iron removed from the IRIS tubes during the period studied ranged between 4 and 96%. The intensity of reduction in the soil differs according to subtle topographic differences between sites; it increases with the decrease in elevation. The large soil salinity (electrical conductivity saturated soil extract, ECe, from 18.1 to 182 dS m-1), carbonate-rich composition (from 18.4 to 69.7% calcium carbonate equivalent, CCE) and overall small organic matter content (from 0.4 to 6.2% organic matter) do not seem to constrain iron mobilization because of the reducing conditions. Differences in iron depletion and patterns on the IRIS tubes show the heterogeneity of soil conditions and the complexity of factors involved in redox processes. Further research is needed to gain knowledge of the redox processes in the context of pedogenesis in semiarid lacustrine environments. Highlights How soil intermittently exposed to waterlogging expresses redox conditions., Current reducing conditions are evident in a fluctuating saline lake by IRIS tubes., Soil reduction occurs in alkaline soil with intermittent waterlogging., IRIS tubes are suitable field indicators of the heterogeneity of soil reducing conditions in saline lakes. [ABSTRACT FROM AUTHOR]

This article presents obtaining the frequency response in transformers, in service (on-line FRA test), through the injection of controlled signals and employing a new algorithm for the analysis of transitory signals. A system hardware was used for the injection of controlled pulses on the 60 Hz; this system can inject signals and change its amplitude, width and phase, ensuring a high spectral content and control of it. According to the results, it was observed how the new method provided greater confidence in the results, so the place to bring a reliable on-line transformer monitoring through the FRA technique is innovative and much interest to electric utilities, because now in the FRA test will be not necessary to interrupt the power supply, eliminating the high costs generated by having to de energized the transformer, the importance of the implemented system is that is capable to monitor the transformer from a smart grid in order to make timely decisions in the actual state of operation based on the equipment condition. [ABSTRACT FROM AUTHOR]

Transitional areas of lake margins are complex environments whose evolution is strongly controlled by flooding frequency and persistence. The edaphic development of lacustrine marginal environments can be reconstructed by combining detailed geomorphological analysis with a systematic edaphic study of toposequences. This approach has been applied to a set of recent lacustrine terraces in the downwind palustrine area of the Gallocanta saline lake, located in a semiarid area in NE Spain. Up to five terraces, from 1.6 to 4.5 m above the lake bottom, have been identified and mapped using stereo photointerpretation and airborne LiDAR data. Several cycles of water level fluctuations, as part of a general trend towards lake desiccation, have generated stepped terrace levels. The soils of these terraces have different morphological characteristics and provide evidences for the Gallocanta paleolake being larger than that of the present day. The soils have a sandy loam texture with variable clay content (1% to 46%) and a predominantly carbonate composition (mean = 26%). The soils are developed in a sequence of lacustrine carbonate-rich (mean = 37%) fine-grained gray layers overlaying detrital (mean = 51% gravels) and frequently erosive, carbonate-poor reddish layers. The pedogenesis of the downwind palustrine area is mainly characterized by poorly-developed carbonate accumulations and common redox mottles associated with water level fluctuations in the lake, which continuously rejuvenate or truncate the soils. Integrating pedological and geomorphological features provides insight into recent complex lacustrine and soil forming processes and facilitates management strategies and plans for this protected saline environment. [ABSTRACT FROM AUTHOR]

Background Kidney transplant patients with D+/R+ serology can be treated with either prophylaxis or preemptive valganciclovir. The older transplant population suffers severe immunosenescence, especially patients with latent cytomegalovirus (CMV) infection (R+). They are more likely to develop indirect CMV effects. Likewise, many patients have significant cardiovascular comorbidity, which makes them more sensitive to these indirect effects. The aim of this study was to evaluate the incidence of CMV viremia and indirect effects on survival, comparing prophylaxis (V) against preemptive (P) valganciclovir in an older kidney transplant population. Methods We analyzed the data of 233 recipients from 2002 (age, >55 years; D+/R+) with ≥6 months of follow-up. The patients were divided into 2 groups: 167 (71.7%) in the V group and 66 (28.3%) in the P group. Results The incidence of CMV infection in the P group was 32% versus 6% in V group. Patients with CMV viremia showed worse survival values than patients without viremia (log rank P = .031). Five-year survivals were 74% vs 88%, respectively. Cox regression showed that the adjusted effect of CMV infection on overall survival was a significant risk (hazard ratio [HR], 2.07; 95% CI, 1.003–4.29). Patients with CMV viremia showed worse cardiovascular survival than patients without viremia, with 5-year survivals of 79% vs 94%. Cox regression showed that the adjusted effect of CMV infection was a significant risk (HR, 2.62). Conclusions CMV infection has a detrimental effect on the survival of older patients. Valganciclovir prophylaxis induces a protective effect against CMV infection and could improve survival of older patients with cardiovascular comorbidities. [ABSTRACT FROM AUTHOR]

Introduction We evaluated analytical and clinical performances of IgG and IgM anticardiolipin ( aCL) antibodies and anti-β2-glycoprotein I (a-β2GpI) antibodies and upper limit reference ranges (99th percentiles) in comparison with manufacturer's cutoff values with different commercial methods. Methods We assayed aCL and a-β2GpI in serum samples from 30 healthy individuals, 77 patients with antiphospholipid syndrome ( APS) diagnosed according to the Sydney criteria, 51 patients with autoimmune diseases, eight patients with previous thrombotic events, six patients with other diseases, and 18 patients with infectious diseases, using ELISA Inova Diagnostics; EliA Phadia Laboratory Systems; CliA Zenit- RA; and CliA Bio-Flash. Results Anticardiolipin and a-β2GpI IgG and IgM immunoassays showed good analytic performances with both 99th percentile and manufacturer's cutoff reference values. Our results showed fair to moderate agreement among assays. In-house cutoff values gave significantly better performances only for a-β2GpI IgG with all the immunoassays analyzed with the exception of Inova CliA Bio-Flash where we obtained the same performances with in-house and manufacturer's cutoffs. Conclusions By guidelines, all laboratories are strongly advised to validate/verify the manufacturer's cutoff values. We recommend establishing low-positive, medium-/high-positive, and high-positive CliA IgG aCL and a-β2GpI ranges in order to help clinicians in the diagnosis and treatment of APS. [ABSTRACT FROM AUTHOR]

Abstract: In their struggle for life, plants can employ sophisticated strategies to defend themselves against potentially harmful pathogens and insects. One mechanism by which plants can increase their level of resistance is by intensifying the responsiveness of their immune system upon recognition of selected signals from their environment. This so-called priming of defence can provide long-lasting resistance, which is based on a faster and/or stronger defence reaction upon pathogen or pest attack. Priming can target various layers of induced defence that are active during different stages of the plant–attacker interaction. Recent discoveries have extended our knowledge about the mechanistic basis of defence priming and suggest that a primed defence state can be inherited epi-genetically from defence-expressing plants. In this review, we provide an overview of the latest insights about defence priming, ranging from early responses controlled by adjustments in hormone-dependent signalling pathways and availability of signal transduction proteins, to longer lasting mechanisms that involve possible regulation chromatin modification or DNA methylation. [Copyright &y& Elsevier]

Objectives: To determine the nutritional status of patients admitted to hospital for the first time the hematology service and who have not received treatment for cancer, to know if the nutritional status assessed by the EGS-GP and serum albumin related mortality of patients Methods; A longitudinal, prospective, analytical. EGSThrough GP assessed the nutritional status of patients, we used SPSS 19.0 for data analysis. Results: Evaluaron 119 patients, 52.1% female and 47.9% male. The most common diagnosis was non- Hodgkin lymphoma in 43.7%. According to the EGS-GP 50.4% of patients had some degree of malnutrition or was at risk of suffering of which: 31.1% had moderate and 19.3% had severe malnutrition. The 49.6% of patients had an adequate nutritional status. 30.3% of the patients who died, 37% had severe malnutrition and 50% severe decrease in albumin concentration. Conclusions: The prevalence of malnutrition in hematological patients treated at the National Cancer Institute of Mexico that have not received medical treatment was high. There is an association between nutritional status and mortality in this patient group. [ABSTRACT FROM AUTHOR]

This paper proposes a method to select an appropriate mother wavelet for the frequency analysis of electrical transient signals, based on the wavelet properties and considering the needs of the application case. The Wavelet Packet Decomposition (WPD) was used to analyze wavelets as filters and to quantify the information leakage by evaluating the performance of different families included in the Matlab's libraries. To validate the method proposed, an application case is presented where the effective value (RMS) is estimated for a transient signal. The selection method used provides a clear scope on how to exploit the wavelet properties to select the appropriate one depending on the particular application. [ABSTRACT FROM AUTHOR]

The local element distribution across tensile-strained N δ-doped (In,Ga)As/GaAs quantum wells (QWs) is investigated by transmission electron microscopy. The sub-monolayer (ML) insertion results in a several monolayers thick (In,Ga)(As,N) layer with lateral composition fluctuations. We also find an inhomogeneous In incorporation across the QW, with a minimum In content, [In]min, exactly at the position of the N-insertion, where N content is maximum, [N]max. Regardless of the position along the QW, [N]max corresponds to [In]min so that an (In,Ga)(As,N) layer of this composition has a lattice parameter close to aGaAs. The impact of tensile strain on this complex chemical configuration is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Background: The change from calcineurin inhibitors (CNI) to sirolimus (SRL) is a safe alternative in transplant patients with neoplasia (NEO) whereas the results of conversion for chronic allograft nephropathy (CAN) are controversial, depending on the histologic score, degree of proteinuria, and glomerular filtration rate (GFR). Our aim in this study was to compare GFR, proteinuria, albuminuria, blood pressure (BP) effects, and anemia after switching to sirolimus (SRL) among renal transplant recipients with CAN versus NEO. Methods: Fifty-five kidney transplant recipients with conversion from CNI to SRL owing to CAN or NEO were analyzed for the variables at 6 months before, at the time of, and at 6 months and 1, 2, and 3 years after the switch to SRL. Results: There were no differences between CAN and NEO in the slope of estimated GFR (mL/min/1.73 m2 by Cockcroft-Gault formula) at 1 year (−5.5 vs 3.7; P = .007) and at 2 years (−3.86 vs −10.3; P = .01). The values of proteinuria (mg/24 h/1.73 m2) before (665 ± 136 vs 329 ± 69; P = .036) as well as at 1 (1,122 ± 306 vs 863 ± 190; P = .478) and at 2 years after conversion (1,360 ± 430 vs 457 ± 154; P = .045) showed some significant differences, as did the use of both antiangiotensin agents, angiotensin-converting enzyme inhibitor and angiotensin receptor blocker at the moment of switch (35% vs 0%; P = .005) at 1 year (69% vs. 6% P = .02) and at 2 years (67% vs 28%; P = .047). There were no differences in graft survival (log rank: P = .515). By logistic regression analysis, the best covariate associated with GFR >45 mL/min at 2 years was GFR >60 mL/min at the moment of switch to SRL (odds ratio, 1.33; 95% confidence interval, 1.002–1.74). Conclusions: The evolution of renal damage was more important in the CAN group requiring greater use of 2 angiotensin antagonists for control of proteinuria. We probably need histologic and serologic biomarkers to show which patients with CAN will show a bad evolution after the change to SRL. [Copyright &y& Elsevier]

We study the case when the triple-Pomeron vertex is assumed to have a vectorial form, that is, the amplitude of high-mass diffractive dissociation vanishes as $V\propto \vec{q}_{t}\cdot\vec{e}$ as q→0. We find that the available data in the triple-Reggeon region may be well described in such a 'weak' coupling scenario, providing that absorptive effects are taken into account. We compare this weak-vector coupling scenario with the strong and weak-scalar coupling scenarios. Corresponding predictions are presented for an LHC energy of 14 TeV. [ABSTRACT FROM AUTHOR]

Abstract: Low energy shifted photoluminescence from isolated erbium ions incorporated into a-SiGe:H thin films is reported. The Er3+ are thermally diffused from an a-SiGe:H:Er layer to a-SiGe:H subsequently grown, both by magnetron sputtering. The photoluminescence observed is associated with transitions produced by erbium emission centers activated by the oxidation in a 1h annealing process in air at 250°C. The resultant Er3+ concentration observed from the a-SiGe:H is affected by the hydrogen concentration already present in the layer. It is observed that at higher hydrogen concentrations in a-SiGe:H the resultant amount of diffused Er3+ decreases. As a consequence of the resultant smaller density of erbium ions, the probability of having isolated Er3+ ions increases. In this last regime, a correlation with stronger photoluminescence is observed. [Copyright &y& Elsevier]

Abstract: Transmission electron microscopy (TEM) techniques are applied to characterize the interfaces of epitaxial III–V semiconductor heterostructures with high spatial resolution and to analyze compositional variations at interfaces. As expected, realistic interfaces of compound semiconductors are not chemically sharp but there is a transition region at the interface. The functional dependence of the smooth change in composition is sigmoidal and can be described using an analytical expression, thus enabling a quantitative characterization of the interface width. The model gives a very good description of the distribution profiles and applies to several material systems, including the interfaces of As-based alloys and those of the non-common-atom InAs/GaSb short-period superlattices. The analysis of (Ga,In)(N,As)/GaAs quantum wells reveals that there is a connection between the interface properties in this material system and the miscibility gap of the alloy. [Copyright &y& Elsevier]

Abstract: A comparative study of the influence of Sb and N ion concentration on the properties of GaInNAs (GINA) quantum wells (QWs) is presented. We find that for perfect two-dimensional (2D) QW there is no direct perceptible improvement in structural quality due to the introduction of Sb. Moreover, contrast variations in the QW suggest an inhomogeneous Sb incorporation. A different behaviour of the integrated photoluminescence (PL) intensity with temperature is observed when comparing the 2D samples grown with/without Sb. Regarding the GINA QWs exhibiting a three-dimensional (3D) morphology, we observe a significant improvement in structural quality for the samples grown with added Sb, as well as for those Sb-free samples but grown under a low N- ions density. Nevertheless, 2D and 3D samples show clear common properties: the GINA:Sb QWs exhibit an improved PL efficiency, but only at high temperatures. On the contrary, the Sb-free samples grown under a low N- ions concentration exhibit a brighter PL at all temperatures considered. [Copyright &y& Elsevier]

We describe the formalism and present the results for a triple-Regge analysis of the available pp and $p\bar{p}$ high-energy data which explicitly account for absorptive corrections. In particular, we allow for the gap survival probability, S 2, in single-proton diffractive dissociation. Since for pp scattering the value of S 2 is rather small, the triple-pomeron vertex obtained in this analysis is larger than that obtained in the old analyses where the suppression caused by the absorptive corrections was implicitly included in an effective vertex. We show that the bare triple-pomeron coupling that we extract from the pp and $p\bar{p}$ data is consistent with that obtained in a description of the γ p→ J/ ψ+ Y HERA data. The analyses of the data prefer a zero slope, corresponding to the small size of the bare vertex, giving the hope of a smooth matching to the perturbative QCD treatment of the triple-pomeron coupling. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we present a detailed transmission electron microscopy analysis of the interfacial structure and composition uniformity of (Ga,In)(N,As) quantum wells grown by molecular beam epitaxy on vicinal GaAs(111)B substrates. Vertical composition fluctuations inside the (Ga,In)(N,As) quantum well are detected depending on the growth conditions, in particular the V/III flux ratio and the growth rate. This vertical composition fluctuation due to the phase separation tendency is in contrast to the (001) case, where the fluctuations proceed in the lateral direction. The specific character of the phase instabilities is discussed with respect to the spinodal decomposition of the (Ga,In)(N,As) alloy grown by step-flow on the misoriented (111)B substrates. The vertical composition fluctuations are explained by the formation of step bunches of alternating composition as a consequence of the different propagation velocity of steps with different atom terminations. [Copyright &y& Elsevier]

Within a QCD-based eikonal model with a dynamical infrared gluon mass scale we discuss how the small x behavior of the gluon distribution function at moderate Q2 is directly related to the rise of total hadronic cross-sections. In this model the rise of total cross-sections is driven by gluon–gluon semihard scattering processes, where the behavior of the small x gluon distribution function exhibits the power law xg(x, Q2) = h(Q2)x-∊. Assuming that the Q2 scale is proportional to the dynamical gluon mass one, we show that the values of h(Q2) obtained in this model are compatible with an earlier result based on a specific nonperturbative Pomeron model. We discuss the implications of this picture for the behavior of input valence-like gluon distributions at low resolution scales. [ABSTRACT FROM AUTHOR]

Transmission electron microscopy (TEM) is used to determine the composition of quaternary (Ga,In)(N,As) quantum wells (QWs). Through a combined analysis of the chemically sensitive (002) dark-field (DF) images and the lattice-resolving high-resolution TEM images, the local distributions of nitrogen and indium in the growth direction are determined. In particular, we are able to directly detect the existence of indium segregation in (Ga,In)(N,As) QWs. A comparison with the indium distribution profile in the nitrogen-free (In,Ga)As QWs, grown under similar conditions, revealed that incorporating N into the alloy enhanced indium segregation. [ABSTRACT FROM AUTHOR]

The increased expression of heat shock protein (Hsp)60 in different kinds of graft tissues has been associated with a proinflammatory role and rejection. However, there are very few reports in which treatment with Hsp60 delays skin allograft rejection. The aim of this work was to evaluate the capacity of encapsulated human Hsp60-derived peptide p277 to delay graft rejection in two murine models of skin transplantation with minor antigen disparities. Briefly, BALB/c mice and C57BL/6 were intranasally pre-treated with five doses of Hsp60 p277 peptide encapsulated in polylactide-co-glycolide acid microspheres (PLGM), and received skin grafts from DBA2 mice and 129/B6 (F1) mice respectively. The treatment with the peptide increased skin graft survival more than 20 days in both the mouse strains, mainly in C57BL/6 recipients ( P < 0.05). Also, p277-treated BALB/c and C57BL/6 mice showed IL-10 and IFN- γ production, induced by p277 peptide. For the first time, a mucosal schedule using the Hsp60 C-terminal peptide p277 encapsulated in PLGM showed some survival prolongation of skin grafts bearing minor antigen disparities. Our results suggest a potential role for Hsp60-based therapy and the mucosal route as a useful tool to control the inflammatory response to allografts. [ABSTRACT FROM AUTHOR]

Autoreactivity to heat shock protein 60 (Hsp60) has been implicated in the pathogenesis and regulation of chronic inflammation, especially in autoimmune diseases. In transplantation, there is a lack of information regarding the cytokine profile and specificity of cells that recognize self-Hsp60 as well as the kinetics of autoreactivity following transplantation. We studied the cellular reactivity of peripheral and graft-infiltrating lymphocytes against Hsp60 in renal transplant patients. Cytokine production induced by this protein in peripheral blood mononuclear cells indicated a predominance of interleukin (IL)-10 during the late post-transplantation period, mainly in response to intermediate and C-terminal peptides. Patients with chronic rejection presented reactivity to Hsp60 with a higher IL-10/interferon (IFN)-γ ratio compared to long-term clinically stable patients. Graft-infiltrating T cell lines, cocultured with antigen-presenting cells, preferentially produced IL-10 after Hsp60 stimulation. These results suggest that, besides its proinflammatory activity, autoreactivity to Hsp60 in transplantation may also have a regulatory role. [ABSTRACT FROM AUTHOR]

Abstract: Millimeter-wave diagnostics at JET, mainly reflectometry, are employing state of art electronics, but are limited in performance by the existing waveguides and antenna system that are inadequate and obsolete. The use of long run waveguides with high losses and non-optimized antennas (in some cases, not pointing to relevant plasma positions) lead to difficult measurement conditions for reflectometry. The new access system presented in this article has been designed to improve the performance of reflectometry measurements and enable the installation of antennas for oblique viewing ECE. These two new antennae will allow the ECE radiation to be collected at different angles with respect to the magnetic field. This set-up, known as oblique ECE , is expected to be extremely useful in improving the interpretation of ECE temperature measurements in all fusion experiments with significant additional heating. For reflectometry, there is an urgent need to improve the edge density measurements as both the lithium beam and Thomson scattering exhibit limitations of resolution at lower densities. The project proposal states that the expected improvement in reflectometry S/N ratio is 30dB. If realized, this will allow broad band reflectometry, for the measurement of the electron density profile, for the first time in JET. [Copyright &y& Elsevier]

Abstract: The double barrier quantum well (DBQW) structure based on AlGaAs/AlAs/GaAs represents a promising design for infrared detectors operating in the 3–5μm range. Nevertheless, this structure is affected by some unexpected and intriguing features which must be taken into account for its practical operation, i.e. the remarkable photovoltaic (PV) effect observed in detectors doped in the QW and the appearance of anomalies in the dark current (I d) characteristics at T &#60;60K. In this work, we focus on the study of the anomalies in I d, in particular the presence of a non-zero current (offset) at zero bias. We report that the offsets are time independent, with negligible hysteresis effects. Additionally we find a closely link between the offsets and the unintentional PV response. Although so far we do not have any clear explanation for the offset, we have found that its appearance may relate to a change in the preferential escape direction of electrons in the dark, which is related to a change from tunnelling-assisted thermionic emission to tunnelling emission. This interpretation is based on the experimental result that the temperature at which the offset first appears agrees with the transition temperature in the mechanisms controlling I d and with the temperature where a reversal in the electron flux direction is found. These results are reproducibly found in all the DBQW samples we have studied. [Copyright &y& Elsevier]

Abstract: In the present work, the nonisothermal imbibition process in a porous medium was numerically analyzed using a non-Darcian model for the momentum equation and energy equations for the wetting and dry zones. In order to show the thermal character of the problem, we assume initially that the porous medium is found at a uniform temperature and suddenly begins the imbibition process into the porous medium with a penetrating fluid at temperature . The physical influence of nondimensional parameters such as Peclet number, Pe, effective heat capacity number, , porous Reynolds number, , and the inertial coefficient of the porous medium, F, serve us to evaluate the position and velocity of the imbibition front as well as temperature profiles in both zones. In particular, for values of , we recover a type of nonisothermal Washburn law. The numerical predictions show that the imbibition front and the temperature fields strongly depend on the above nondimensional parameters, revealing a clear deviation of the simple Washburn law. [Copyright &y& Elsevier]

We have grown GaInSbBi single layers and GaInSbBi/GaSb multiquantum well (MQW) structures by molecular beam epitaxy. We observed that the addition of In strongly modifies and reduces the Bi incorporation into GaSb. For an In concentration of ∼3.7%, we reached a maximum Bi content of 10.5% while the highest Bi concentration falls to 3% with 10% of In. Additionally, droplets appear at lower Bi composition than in GaSbBi alloys. Finally, the optical properties of GaInSbBi/GaSb MQW structures were characterized by photoluminescence spectroscopy at room temperature. The longest emission wavelength observed was close to 2.6 μm for a composition of 10.5% and 3.7% of bismuth and indium, respectively. [ABSTRACT FROM AUTHOR]

In this work, an analysis is done on the sudden injection of gaseous nitrogen in a porous cap filled initially with natural gas. A cylindrical geometry has been selected to derive the mathematical model. The resulting nondimensional governing equations for the pressure of the binary mixture and the corresponding nitrogen concentration are solved numerically using conventional finite difference techniques. The numerical results show that the injection process is sensibly controlled by several nondimensional parameters, which have a clear influence in order to define the corresponding nitrogen distribution throughout the cap. [Copyright &y& Elsevier]