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This paper presents an observer-based event-triggered strategy for linear systems subject to input cone-bounded nonlinearities. Both the emulation and co-design problems are addressed. Considering a Lyapunov approach and the cone-bound property of the input nonlinearity, sufficient conditions based on linear matrix inequalities are derived to ensure regional or global asymptotic stability of the origin of the closed-loop system. These conditions are incorporated into convex optimization problems to optimally determine the event generator parameters and the controller gain (in the co-design case) aiming at reducing the number of control updates with respect to periodic implementations for a prescribed observer gain. The event-triggering strategy considers a dwell time to cope with Zeno behaviors. Numerical examples, considering systems with quantized logarithmic inputs and saturating inputs, illustrate the potentialities of the approach. [ABSTRACT FROM AUTHOR]

Abstract Ethanol is a promising renewable fuel for spark ignition engine and it can be blended with gasoline in the full range from pure gasoline to 100% ethanol. The objective of this study is to investigate the influence of ethanol content on the research octane number (RON) of a gasoline surrogate. A four-component gasoline surrogate containing iso -octane, n -heptane, toluene and di - iso -butylene is formulated, and the experiments are conducted using seven gasoline surrogate/ethanol blends in a Cooperative Fuel Research (CFR) engine operating according to the standard ASTM D2699. The results of this study show that RON increases with the addition of ethanol, from 89.4 (E0) to 108.6 (E100), but without a linear dependence of RON on the volumetric ethanol content. Moreover, air/fuel ratio and overall burning angle tend to decrease with the increase of ethanol content, while in-cylinder pressure and indicated mean effective pressure are affected positively. The results reported in this study contributes to the acquisition of data for quinary surrogates, since the fuel under investigation is an ethanol-containing four-component gasoline surrogate. [ABSTRACT FROM AUTHOR]

In linear elastic fracture mechanics, the rate of crack propagation is proportional to the range of stress intensity factors. The most popular model relating these quantities is the Paris–Erdogan law. Crack growth computation is an initial value problem whose solution cannot be obtained in closed form, as stress intensity factors, hence crack growth rates, depend on the accumulated growth. For complex geometries, stress intensity factors are evaluated numerically, and crack growth computations can become computationally intensive. This paper presents a theoretical result establishing upper and lower bounds for the crack size function for any number of cycles. The bounds are very narrow, hence accurate crack size approximations can be obtained from only two stress intensity factor evaluations. This leads to a huge gain in computational effort for numerical crack growth computations. Two examples are used herein to explore the accuracy and efficiency of the proposed solution for the crack growth initial value problem. [ABSTRACT FROM AUTHOR]

Circulating memory B cells are considered as the main reservoir for Epstein-Barr virus. Several studies identified the presence of Epstein-Barr virus-infected B cells in the lesions of Crohn disease and ulcerative colitis suggesting that colon mucosa with chronic inflammation could be a potential site of Epstein-Barr virus replication. However, whether skin could be also an Epstein-Barr virus reservoir has not yet been investigated. We used pilonidal cysts as a model of skin chronic inflammation, and we found in 20 (55.6%) of 36 cases variable amounts of Epstein-Barr virus-infected cells as assessed by in situ hybridization using Epstein-Barr virus-encoded RNA probe and immunostainings. Most (95%) of the Epstein-Barr virus-positive cells were of B-cell phenotype, whereas scattered cells were double stained with Epstein-Barr virus-encoded RNA probes and T-cell markers. Epstein-Barr virus-encoded RNA+ cell density correlated with the intensity of inflammation. This density was similar to that observed in chronic diverticulitis but higher when compared with appendicitis, suggesting that chronic rather than acute inflammation facilitates the recruitment of Epstein-Barr virus-infected cells in diseased tissues. Altogether, these data suggest that, in immunocompetent patients, skin inflammatory lesions contain Epstein-Barr virus-infected cells exhibiting latency type I. Moreover, skin-like gastrointestinal mucosa is a potential site of Epstein-Barr virus replication and spreading. Our results may explain the pathogenesis of the Epstein-Barr virus-positive mucocutaneous ulcer. [ABSTRACT FROM AUTHOR]

To evaluate a nested PCR protocol for Listeria monocytogenes detection, Minas Frescal cow's milk cheeses were produced, artificially inoculated with this pathogen at concentrations ranging from 1 to 1,000 CFU/g, and stored at 4°C for 10 days. The International Organization for Standardization (tSO) standardized method 11290-1/A1 was used to detect L. monocytogenes in the inoculated samples, and DNA was extracted from aliquots (1, 5, and l0 ml) of 1:10 dilution, followed by a nested PCR protocol for the hlyA gene. The ISO standardized reference method and nested PCR both detected L. monocytogenes at all concentrations and during all storage periods; McNemar's test showed no significant difference (P > 0.05). The results indicated that the nested PCR protocol can be used as a screening test to detect L. monocytogenes in Minas Frescal cheese, allowing earlier detection of the pathogen that can later be confirmed by the ISO standardized reference method. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the method of Galerkin and the Askey–Wiener scheme are used to obtain approximate solutions to the stochastic displacement response of Kirchhoff plates with uncertain parameters. Theoretical and numerical results are presented. The Lax–Milgram lemma is used to express the conditions for existence and uniqueness of the solution. Uncertainties in plate and foundation stiffness are modeled by respecting these conditions, hence using Legendre polynomials indexed in uniform random variables. The space of approximate solutions is built using results of density between the space of continuous functions and Sobolev spaces. Approximate Galerkin solutions are compared with results of Monte Carlo simulation, in terms of first and second order moments and in terms of histograms of the displacement response. Numerical results for two example problems show very fast convergence to the exact solution, at excellent accuracies. The Askey–Wiener Galerkin scheme developed herein is able to reproduce the histogram of the displacement response. The scheme is shown to be a theoretically sound and efficient method for the solution of stochastic problems in engineering. [Copyright &y& Elsevier]

Abstract: In this work, we develop an analog circuit to generate a stochastic signal with stationary distribution exhibiting a tunable power-law tail. The proposed circuit design is a variant of a recently introduced one based on a differential equation with both multiplicative and additive noises. Here, the circuit is carefully designed in order to ensure that all components operate within their specific regimes. We provide a detailed characterization of the output signal, including the power-law exponent dependence on the tunable component. We apply the present circuit to study the first passage time problem in a simple integrate-fire model of neural dynamics driven by a non-Gaussian noise. [Copyright &y& Elsevier]

Delaminated areas produced by ballistic impacts on a ±45° glass–fabric composite were measured by digital image analysis. The post-impact performance of the composite, as measured by the tensile stiffness and Charpy impact energy of macroscopically undamaged, delaminated and bullet trespassed specimens was determined, and correlated to the effect caused by the presence of the delaminated areas. The results obtained show that two conditions must be satisfied so that delaminated areas seriously affect the post-ballistic behavior of the composite, namely: the presence of shear stresses and delaminated areas above a threshold value. [Copyright &y& Elsevier]

The activity of PGLa, an antimicrobial peptide isolated from hemocytes of frog skin and its secretions on living Escherichia coli, was investigated by imaging the cells with atomic force microscopy (AFM) in physiological conditions and by measuring its cellular stiffness. The treatment of bacteria with the antimicrobial peptide PGLa in the culture medium had two stages. The first was characterized by the loss of surface stiffness and consequent loss of bacteria topographic features and the formation of micelles probably originating from the disruption of the outer membrane. The formation of outer membrane originated micelles is in agreement with the carpet-like mechanism of action proposed for antimicrobial peptides of the magainin family. The peptide action also resulted in the removal of bacterial pili. In a second stage there was further damage which resulted in total cell rupture. The addition of Mg2+ ions prior to peptide treatment partially inhibited the effects of PGLa on bacteria. This result suggests that PGLa interacts with the outer membrane by displacing Mg2+ from LPS, inserting itself into the bilayer and cross-bridging the negative charges of LPS lipids as proposed in the self-promoted pathway mechanism. The peptide effect on the bacteria was compared to the activity of the chelating agent EDTA that damages the bacterial outer membrane by removing Mg2+ ions. [Copyright &y& Elsevier]

We report the isolation of a novel antimicrobial peptide, acanthoscurrin, from the hemocytes of unchallenged tarantula spider Acanthoscurria gomesiana. A combination of Edman degradation, mass spectrometry and cDNA cloning revealed the presence of two isoforms of acanthoscurrin, differing by two glycine residues. Both displayed cationic properties and a high percentage of glycine residues. However, acanthoscurrins have no structural similarities with already known glycine-rich antimicrobial peptides from animals and plants. As deduced from cDNA cloning and mass spectrometry, the amino acid sequence of acanthoscurrin begins with a putative signal peptide of 23 amino acids followed by the mature peptide, which is post-translationally modified by a C-terminal amidation. Acanthoscurrins are constitutively expressed in hemocytes and released to plasma following an immune challenge. [Copyright &y& Elsevier]

Activation of neurons in the region of the dorsomedial hypothalamus (DMH), by microinjection of the GABAA receptor antagonist bicuculline methiodide (BMI) results in increases in arterial pressure, heart rate as well as behavioral changes similar to those evoked by acute emotional stress. Previous anatomic studies clearly demonstrated projections from the DMH to the midbrain periaqueductal gray (PAG), a brain region implicated in the organization of behavioral strategies associated with specific cardiovascular responses. In this study, physiological experiments in conscious rats were used to investigate the functional significance of this pathway. Unilateral inhibition of the lateral dorsolateral region of the PAG (l/dlPAG) with the GABAA receptor agonist, muscimol (1 nmol/100 nl) largely reduced the tachycardia and the pressor response produced by microinjection of BMI (10 pmol/100 nl) into the ipsilateral DMH. In contrast, inhibition of the ventrolateral PAG (vlPAG) region had no significant effect on the cardiovascular response evoked from disinhibition of the ipsilateral DMH. Our present results indicate that the l/dlPAG region is an important synaptic relay in the descending cardiovascular pathways from the DMH. [Copyright &y& Elsevier]

A simple simulation scheme that simultaneously describes the growth kinetics of SiO2 films at the nanometer scale and the SiOx/Si interface dynamics (its extent, and spatial/temporal evolution) is presented. The simulation successfully applies to experimental data in the region above and below 10 nm, reproduces the Deal and Grove linear-parabolic law and the oxide growth rate enhancement in the very thin film regime (the so-called anomalous region). According to the simulation, the oxidation is governed mainly by two processes: (a) the formation of a transition suboxide layer and (b) its subsequent drift towards the silicon bulk. We found that it is the superposition of these two processes that produces the crossover from the anomalous oxidation region behavior to the linear-parabolic law. [Copyright &y& Elsevier]

In the present work, we describe the discovery of PW2, a novel peptide presenting in vitro activity against Eimeria acervulina and E. tenella sporozoites. PW2 was selected from phage display (Ph.D.) peptide libraries by an alternative method of panning using living purified E. acervulina sporozoites as targets. Our results showed that the peptide disrupts the sporozoite pellicle, resembling the effect caused by most natural antimicrobial peptides. PW2 peptide was also effective against fungi and showed low activity against Toxoplasma gondii tachyzoites, but no activity against Trypanosoma cruzi, Crithidia fasciculata epimastigotes, and bacteria. Additionally, the parasiticidal concentrations of PW2 produced a very low lytic effect on mammalian and avian cells. The effectiveness against Eimeria sporozoites and the absence of adverse effects to host cells indicates that PW2 may be used as a model to generate new drugs for the control of avian coccidiosis. [Copyright &y& Elsevier]

The author discusses a paper by Abdelaziz Hmamed et al on stabilization under constrained states and controls of positive systems with time delays. He says that the proposed method in the paper allows the computation of a stabilizing state feedback that renders the closed-loop system positive. He suggests that the strong point of the approach is that the stabilizing conditions can be cast as linear programs. An outline of the approach is presented.

Thin polyaniline films in the emeraldine oxidation state, deposited by spin coating on glass substrate when exposed to gamma-irradiation presents an interesting radiochromic effect, very similar to the protonic acid doping of polyaniline. The green color of the irradiated film and the two absorption bands developed at 420 and 832 nm is a strong evidence of the generation of polaron defect (radical cation) which is responsible for the high conductivity of the polymer. In this work we used the Atomic Force Microscopy (AFM) technique to investigate the morphology of polyaniline films irradiated with 60Co gamma rays and compare with protonic acids doping effect. [Copyright &y& Elsevier]

Highlights • Murine BM-DCs produce and respond to LTB4, upregulating BLT-1 expression. • LTB4 stimulation increased CD86 expression in BM-DCs and enhanced their T cell priming activity. • BM-DCs exposed to LTB4 can favor Th2/Treg adaptive immune responses. Abstract Dendritic cells (DCs) link innate and adaptive immunity. The microenvironment generated during the innate immunity affects DCs and the type of adaptive immunity generated. Lipid mediators are released early in inflammation and could modify the functional state of DCs. Leukotriene B 4 (LTB 4) has a wide range of effects on macrophages and in the present study we investigated if it also affects DCs. Murine bone marrow-derived DCs were employed and it was found that stimulation of DCs with LTB4 (10 nM) increased the gene expression of the high affinity receptor BLT-1 but not of BLT-2. It also increased the co-stimulatory molecule CD86 expression but did not affect CD80 and CD 40. LTB 4 -stimulated DCs acquired the capacity to present antigen to T lymphocytes, evidenced by antigen-specific proliferation of CD4+ lymphocytes in co-cultures of ovalbumin-loaded DCs with DO11.10 splenocytes. LTB 4 -stimulated DCs induced Treg proliferation and increased Th2 cytokine IL-13 in the co-cultures. Expression of transcription factor genes, Gata3 and Fox p3 (Th2 and Treg, respectively) were also found increased. However, the expression of Th1 transcription factor (Tbet) and Th17 (RorγT) were not affected. These results indicate that LTB 4 affects DCs and modulates the type of adaptive immune response. [ABSTRACT FROM AUTHOR]

This paper proposes nonlinear control strategies for the discrete-time near time-optimal control of damped servomechanisms. Both the well established Proximate Time Optimal Servomechanism (PTOS) and its dynamically damped version (ddPTOS) are extended for damped systems. Stability results are presented in a general discrete-time framework suitable for both damped and undamped systems. These results allow the reduction of constraints in the traditional PTOS – particularly regarding the acceleration discount factor – while encompassing the nonlinear damping of the ddPTOS. Experimental results demonstrate the efficiency of the proposed controllers. [ABSTRACT FROM AUTHOR]

This work addresses the stability analysis of linear aperiodic sampled-data systems under saturating inputs. A method to generate an increasing sequence of polyhedral estimates of the region of attraction of the origin of the closed-loop system is proposed. An impulsive system representation, given by a linear flow and a nonlinear jump dynamics due to the saturation term, is employed. From this representation, a convenient partition of the admissible interval for the intersampling time and an appropriate model of the saturation term, the computation of polyhedral contractive sets is carried out considering a convex embedding of the behavior of the system at the sampling instants. It is then shown that the computed polyhedra are included in the region of attraction of the continuous-time plant driven by the sampled-data control. A numerical example validates the theoretical developments and compares the method presented in this work with other approaches from the literature. [ABSTRACT FROM AUTHOR]

Despite the wide range of institutions that maintain venomous snakes in captivity in Brazil there are no comprehensive data on the occurrence of snakebites and envenomations in these places. We examined the range of native and exotic species of venomous snakes kept by Brazilian zoos and serpentaria (scientific and commercial) and assessed the frequency of snakebites in workers handling these snakes during a 10-year period (2012–2021). Twenty-two (73.3%) of 30 institutions returned a standard questionnaire, including 15 serpentaria and 7 zoos that together kept 10,607 venomous snakes in 2022/2023. Commercial and scientific serpentaria had many more snakes (n = 10,550, consisting of 10,499 native specimens and 51 exotic specimens) than zoos (n = 57 native specimens), with two genera accounting for the majority of native species (Bothrops spp. = 84.5% and Crotalus durissus ssp. = 13.5%). Thirty-seven snakebites were reported and involved primarily the hands (33), seven of which occurred during venom extraction and 30 in other circumstances, most of them while handling/manipulating the cages or snake boxes (10) and restraining (9) or feeding (5) the snake. In addition, there were two cases of venom accidently sprayed on the face, including the eyes. Most bites were caused by Bothrops spp. (31), followed by C. durissus ssp. (4), Lachesis muta (1) and Micrurus corallinus (1). Thirty-three bites (89.2%) were treated with antivenom, with four bites to the fingers by Bothrops spp. resulting in local functional sequelae. There were 366,918 venom extractions with a ratio of 1.9 bites/100,000 extractions; no bites were recorded in the six institutions that sedated the snakes prior to venom extraction, which accounted for 22.7% of all extractions. These findings show that although snakebites are rare in Brazilian zoos and serpentaria, severe envenomation may occur. The occurrence of snakebites could be reduced by measures such as sedation of the snakes before venom extraction. [Display omitted] • Few studies have addressed snakebites by captive venomous snakes. • The range of venomous snakes kept by Brazilian zoos and serpentaria was assessed. • Twenty-two officially registered institutions kept 10,607 snakes in 2022–2023. • Thirteen institutions performed 366,918 venom extractions from 2012 to 2021. • There were 37 snakebites during the period, with seven during venom extraction. [ABSTRACT FROM AUTHOR]

Background: It is unclear whether participation in exercise programs specifically developed for elderly translates into a more active lifestyle. Objectives: To compare the objectively measured level of physical activity in daily life (PADL) between physically independent elderly who participate or do not participate in community-based exercise programs; and to evaluate which factors are associated with the higher level of PADL in these subjects. Method: 134 elderly participants in community-based exercise programs (PG) and 104 non-participants (NPG) had their level of PADL measured using pedometers during 7 days. Other measurements: 6-minute walking test (6MWT), incremental shuttle walking test (ISWT), muscle strength, flexibility and balance. Results: The PG had higher 1-week mean daily step count than NPG (8314 [IQR 5971-10060] vs. 6250 [IQR 4346-8207] steps/day, p<0.0001), as well as higher step count in any day of the week. There was a higher proportion of physically active subjects (≥8000 steps/day) in PG than in NPG (37% vs. 16%, respectively; p<0.001), as well as the proportion of sedentary subjects (<5000 steps/day) (14% vs. 33%, respectively; p<0.001). Participation in exercise programs, 6MWT and ISWT explained a higher daily steps count (model r2=0.56, p<0.0001). Conclusions: In physically independent elderly, a higher level of physical activity in daily life occurs in those who participate in community-based exercise programs, regardless of the weekday and including non-program days. Participation of elderly in community-based exercise programs should be more systematically available and encouraged due to its close link to higher activity levels and better exercise capacity. [ABSTRACT FROM AUTHOR]

We address the effects imposed by localized interfacial states on the electronic structure of silicon nanocrystals embedded in ultrathin SiO2 films. The modeling used describes the charged interface defects through a δ(r) attractive potential within the effective mass approximation. The results show that the coupling among defect position, nanocrystal shape and effective mass tensor shifts the energy levels of the conduction band by tens of meV, causing dramatic changes to the overall nanocrystal electronic structure. [Copyright &y& Elsevier]

The synthesis, characterization and TG–DSC study of the compounds CdX2·ncaff, for which X: Cl, Br and I; n=1 and 2 and caff: caffeine is reported. It is verified that caffeine is coordinated through more than one coordination site, despite the fact that the nitrogen of the imidazole ring is the main coordination site. The following thermal stability trend is observed: Cl>Br>I and monoadducts are more stable than bisadducts. The thermal degradation (td) enthalpies have the values (kJ mol−1): 58.2 and 71.5; 74.9 and 91.4; 31.1 and 47.5 for Cl, Br and I mono and bisadducts, respectively. [Copyright &y& Elsevier]

Gomesin is a cationic anti-microbial peptide of 18 amino acid residues isolated from the hemocytes of unchallenged tarantula spider Acanthoscurria gomesiana. This paper reports the first study of the processing and cellular location of an anti-microbial peptide (AMP) in spiders. Gomesin cDNA sequence analysis indicated that it is processed from a precursor containing a signal peptide (23 amino acid residues) and a negative C-terminal region (43 amino acid residues). The gomesin gene was constitutively transcribed in hemocytes and the gene product localized in hemocyte granules. The constitutive production of gomesin by a spider is discussed in the context of an ancient mechanism of AMP regulation and storage. [Copyright &y& Elsevier]

A semi-quantitative RT-PCR protocol was developed to directly evaluate metallothionein (MT) mRNA expression in different tissues of mangrove oysters (Crassostrea rhizophorae), using β-Actin (ACT) as a normalizing gene. Clones with high degree of identity from partial coding sequences were obtained for both MT and ACT. Although not statistically significant, high relative accumulation of MT mRNA was observed in the digestive gland (DGG), but not in the gills, from samples collected from both control and contaminated sites. Nevertheless, MT expression was not comparable to the high levels of metal in the contaminated oysters. Results indicate that the variation in relative MT mRNA levels from different samples of the same site could be due to multiple gene copies or different MT isoform induction. [Copyright &y& Elsevier]

We have developed an ultraviolet dosimeter based on lanthanide β-diketonate complexes nanofilms. The UV photodegradation of the nanofilm photonic properties allows it to act as a dosimeter. To develop a better understanding of this UV photodegradation process, we have performed atomic force microscopy (AFM) and in situ mass spectrometry (under ultraviolet exposure) studies of the nanofilms. The results indicate that the UV photodegradation phenomenon does not lead to any microstructural or morphological changes of the samples. Therefore, we reason that the degradation process should be related to changes in the energy transfer between ligands and the central ion of the complexes or else to the creation of nonradiative pathways corroborating for a luminescence quenching related to the UV exposure dose. [Copyright &y& Elsevier]

Presents inquiry on the stability of linear continuous-time systems. Presentation of notation used in time calculations; Statement of formula in solving for linear continuous-time-delay system; Illustration of an uncertain system formula.

The excitonic properties of CdTe/Cd1−xMnxTe strained quantum wells (QWs) are calculated taking into account interface and electric field effects. Numerical results for CdTe/Cd0.68Mn0.32 QWs show that the broadening of the exciton-related photoluminescence spectra can be as large as 30 meV in the case of interfacial fluctuations of 3 monolayers in 50 A˚ wide strained QWs subjected to a 100 kV/cm electric field. [Copyright &y& Elsevier]

Background: Clinical and laboratory methods have been developed to assess the different dimensions of postural control with the aim to increase the clinical relevance of decisions about balance deficit. Objectives: The purpose of this study was to correlate the force platform measurements with two functional tests used to evaluate balance in elderly. Methods: A total of 124 physically independent elderly volunteers participated in this study. Subjects performed the following three tests: 1) a traditional functional balance test, named the one-leg standing test, which measures the time in seconds at this position; 2) a functional agility/dynamic balance test, which quantifies the total time in seconds that a subject can stand up from a chair and move as quickly as possible around two cones; and 3) an unipodal balance test on a force platform. Results: The one-leg standing test yielded a mean of 12 seconds (SD=9 s), while the mean time observed in the functional agility/dynamic balance test was 26 seconds (SD=6 s). The correlations between the balance parameters of force platform and two functional tests varied between -0.28 and 0.20, which shows a weak association between them. Conclusions: Our results support the idea that these functional tests do not necessarily furnish the same information regarding balance mechanisms as the force platform. This study contributes to the evaluation of balance in elderly and suggests that functional tests should be used with caution especially in regards to the purposes of the research and when conducting clinical assessments of the elderly. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we address modal parameter fluctuations in statistical distributions describing charge-to-breakdown and/or time-to-breakdown during the dielectric breakdown regime of ultra-thin oxides, which are of high interest for the advancement of electronic technology. We reobtain a generalized Weibull distribution (q-Weibull), which properly describes data when oxide thickness fluctuations are present, in order to improve reliability assessment of ultra-thin oxides by time-to-breakdown extrapolation and area scaling. The incorporation of fluctuations allows a physical interpretation of the q-Weibull distribution in connection with the Tsallis statistics. In support to our results, we analyze data of -based MOS devices obtained experimentally and theoretically through a percolation model, demonstrating an advantageous description of the dielectric breakdown by the q-Weibull distribution. [Copyright &y& Elsevier]

In this work, the excitonic properties of ZnSe/ZnSxSe1-x strained superlattices (SLs) and quantum wells (QWs) are studied taking into account spin-orbit splitting, strain, and interfacial effects. The broadening of excitonic related photoluminescence (PL) spectra due to the existence of gradual interfaces with thickness of 10 Å is shown to be of the order of 30 meV for a 30 Å ZnSe/ZnS0.18Se0.82 QW. [Copyright &y& Elsevier]

In this work we present photoluminescence characterization of rare earth ion-doped nanoporous aluminum oxide synthesized by the anodization process in diverse solvents. We find that the luminescence of doped aluminum oxide strongly depends on the synthesis medium. When synthesized in an inorganic acid only rare earth fluorescence is present, whereas nanoporous aluminum oxide synthesized in organic solvent presents two strong unexpected luminescence emission lines, one at 429 nm and the other at 491 nm, with quite long decay time when excited with long wavelength ultraviolet light. The results suggest that light simulation of primary colors and chromaticity control of the emitted light can be done by the a combination of different rare earth ions present in the sample. [Copyright &y& Elsevier]

We calculate the confined exciton energy of zincblende GaN/BN cylindrical nanowires using a two-parameter variational approach within the effective mass approximation. Feasibility of light emission in the 300-700 nm range is attained, depending both on the nanowire radius and the graded interface thickness. It is shown that in actual zincblende GaN/BN nanowire samples, the existence of non-abrupt interfaces can blue shift the exciton recombination energy up to ∼100 meV for non-abrupt interface thickness of just a few monolayers. [Copyright &y& Elsevier]

We study the electronic density of states (DOS) of a GaAs/GaxAl1-xAs superlattice with impurities arranged according to the Fibonacci sequence. Our theory uses a Green function method based on Dyson’s equation within the real-space renormalization-group approach in the framework of the tight-binding Hamiltonian for the Fibonacci quasiperiodic lattice. An exact decimation transformation has been done for the physical parameters characterizing the Fibonacci chain considering the scaling factor, under which the system is self-similar, equal to the golden mean τ=(1+√ of 5)/2. The electronic energy spectrum are then used to determine the electronic specific heat which, due to the localization of the electronic states, exhibits strong Schottky anomalies when the temperature goes to zero together with a log-periodic oscillation. [Copyright &y& Elsevier]

A polypeptide chain formed by recombinant antigens, cytoplasmic repetitive antigen (CRA) and flagellar repetitive antigen (FRA) (CF-Chimera) of Trypanosoma cruzi, was adsorbed on gold and platinum electrodes and investigated by electrochemical impedance spectroscopy on phosphate buffer saline solutions (PBS) containing a redox couple. It was found that the adsorption is strongly sensitive to the oxide layer on the electrode surface. In the majority of the experiments the antigens retained their activity as observed through their interaction with sera from chronic chagasic patients. The results expressed in terms of the charge transfer resistance across the interface, indicate the viability of using the impedance methodology for the development of a biosensor for serological diagnosis of Chagas’ disease. [Copyright &y& Elsevier]