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In x Ga 1 - x As y Sb 1 - y epilayers with a fixed In content of x = 0.145 were grown on GaSb(100) substrates using liquid-phase epitaxy (LPE). The lattice mismatch between the quaternary epilayers and substrates was analyzed for different As contents (y ) by X-ray ω -2 θ . Epilayers with As content between y = 0.120 and y = 0.124 exhibited a positive lattice mismatch, leading to compressive strain. These samples showed a high crystalline quality and flat surfaces, as confirmed by high-resolution X-ray diffraction (HR-XRD) and atomic force microscopy (AFM). Quaternary alloys with As content between y = 0.133 and y = 0.141 displayed a negative lattice mismatch, resulting in tensile strain. Structural defects in these samples were evidenced by HR-XRD and on AFM micrographs. Raman measurements also revealed that lateral strain has a direct impact on the intensities of the LO-like, phonon–plasmon and disorder-activated longitudinal acoustic modes. For all In x Ga 1 - x As y Sb 1 - y films, photoluminescence (PL) spectra showed a bound exciton (BE) transition, with additional features observed in samples under tensile strain, indicating the involvement of native defect centers and donor–acceptor pairs. This study provides new insights into the effect of lateral strain on the crystalline and surface quality, and optical properties of quaternary alloys, relevant for novel optoelectronic applications. [ABSTRACT FROM AUTHOR]

In tuberculosis (TB) vaccine development, multiple factors hinder the design and interpretation of the clinical trials used to estimate vaccine efficacy. The complex transmission chain of TB includes multiple routes to disease, making it hard to link the vaccine efficacy observed in a trial to specific protective mechanisms. Here, we present a Bayesian framework to evaluate the compatibility of different vaccine descriptions with clinical trial outcomes, unlocking impact forecasting from vaccines whose specific mechanisms of action are unknown. Applying our method to the analysis of the M72/AS01E vaccine trial -conducted on IGRA+ individuals- as a case study, we found that most plausible models for this vaccine needed to include protection against, at least, two over the three possible routes to active TB classically considered in the literature: namely, primary TB, latent TB reactivation and TB upon re-infection. Gathering new data regarding the impact of TB vaccines in various epidemiological settings would be instrumental to improve our model estimates of the underlying mechanisms. The complex transmission chain of tuberculosis (TB) forces mathematical modelers to make mechanistic assumptions when modelling vaccine effects. Here, authors posit a Bayesian formalism that unlocks mechanism-agnostic impact forecasts for TB vaccines. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of (E)-3-((S)-1-phenylethylamine)methylene R-(+) camphor are discussed. The 1H NMR spectrum in a chloroform solution indicates the existence of a mixture of two tautomers, the main tautomer corresponds to the E-isomer. On the other hand, in the solid state, the crystal structure solved by X-ray diffraction shows only the occurrence of this latter form. Crystal data: monoclinic (P21), a = 11.019(4) Å, b = 6.782(2) Å, c = 11.186(4) Å, β = 101.843(4)°. [ABSTRACT FROM AUTHOR]

In this work, a simple and economical chemical method was used to synthesize MnSb2O6 nanoparticles for their potential application as a gas sensor. The nanoparticles of the oxide were analyzed by powder X-ray diffraction, finding the crystalline phase at 600 °C. The crystallized oxide presented a hexagonal crystalline structure with spatial group P321. The microstructure of the material was analyzed by field-emission scanning electron microscopy, finding surface morphologies such as micro-plates, microspheres (diameter ~ 0.69 μm), and other particles without apparent shape. The average size of the nanoparticles was estimated at ~ 32.0 nm, according to images obtained by transmission electron microscopy (TEM). Oxidation states of the atomic elements forming the MnSb2O6 nanoparticles were found by X-ray photoelectron spectroscopy measurements. In the case of Mn, two oxidation states Mn2+ and Mn3+ corresponding to the Mn 2p3/2 state were observed at 641.26 and 642.7 eV, respectively. For Sb, the Sb3+ oxidation state, associated with the Sb 3d3/2 state, was located at 539.82 eV. The peak assigned to O at 530.82 eV overlaps the Sb 3d5/2. The secondary ion mass spectrometry depth profiling showed a good distribution of the atomic elements in the nanoparticles, without additional elements or impurities. The optical properties were also studied by photoacoustic spectroscopy, revealing a direct transition of the MnSb2O6 nanoparticles with a band gap energy of 1.78 eV. The gas detection tests were performed in C3H8 and CO atmospheres at different concentrations and operating temperatures. The oxide showed an interesting behavior as the concentrations of the testing gases and the operating temperature increased. The high response presented by the MnSb2O6 suggests that this material can be used as a gas sensor. [ABSTRACT FROM AUTHOR]

Nickel antimonate (NiSb2O6) was synthesized by a microwave-assisted wet chemical method for its application as a potential gas sensor. The powders calcined at 600 °C were corroborated by X-ray diffraction. The microstructure of the material was analyzed by electron microscopy in its scanning and transmission versions, finding different morphologies. The average size of the nanoparticles was estimated at ~ 14.3 nm. X-ray photoelectron spectroscopy showed that the bond energies for Ni (2p) were of 855.2 and 872.9 eV, for Sb, they were of 530.28 and 539.66 eV, and for O(1s), it overlapped the Sb at 530.28 eV. Photoluminescence and UV-Vis spectroscopy measurements confirmed that the emission energy values were of 2.8 and 1.4 eV. Tests carried out in propane and CO atmospheres indicated that the NiSb2O6 nanoparticles possess good response at several concentrations and temperatures of both gases. According to our results, NiSb2O6 is a strong candidate to be applied as a gas sensor. [ABSTRACT FROM AUTHOR]

Samarium colloids in organic solvents (2-methoxyethanol, 2-propanol, 2-propanone, and 1,2-dimethoxyethane) were obtained by the chemical liquid deposition (CLD) method at 77 K. The colloids were characterized by electron diffraction, energy-dispersive X-ray (EDX), UV-Vis spectroscopy, kinetic stability, and electrophoretic measurements. The colloid stability depends on the solvent used and the metal concentration. The higher stability was obtained in 2-methoxyethanol, which is in agreement with previous results for other lanthanide colloids. The zeta potential (ζ) of the colloids ranges between 0.138 and 1.945 mV. The UV-Vis spectra exhibit bands characteristic of the solvent. The 2-methoxyethanol shows bands at 205 and 234 nm very similar to the 2-propanol which exhibits bands at 202 and 253 nm for 2.5E−4 M concentration. However, bands for 1,2-dimethoxyethane and 2-propanone colloids were impossible to determine due to their highest extinction coefficient values. A dependence of the UV/Vis spectral properties of these new sol materials with Sm(III) is described. In all cases, the EDX analyses confirm the presence of metal in the colloids. The electron diffraction gives the most common (hkl) planes corresponding to Sm and SmO (211) and (100), respectively. As shown by the particle size distribution determined from transmission electron microscopy (TEM), the Sm-2-methoxyethanol colloids exhibit ranges from 1.6 and 2.9 nm, but the Sm-2-propanol colloids show ranges from 2.3 to 2.5 nm; the medium particle size of Sm-1,2-dimetoxyethane colloid is 0.8 nm, and the Sm-2-propanone colloids have a range from 1.0 and 4.3 nm, exhibiting a solvent polarity dependence. Also, active solids from the evaporation of the colloids which have been fully characterized by several chemical and physical techniques have been obtained. [ABSTRACT FROM AUTHOR]

Background and aims: Freeze-dried powdered yacon (FDY) can be considered a prebiotic product due to its fructooligosaccharides (FOS) content. The effect of 9 weeks of daily intake of FDY containing 7.4 g of FOS on glucose, lipid metabolism and intestinal transit in a group of elderly people was investigated. Methods: Seventy-two elderly (mean age 67.11 ± 6.11) men and women were studied for 9 weeks in a double-blind, placebo-controlled experiment. They were randomly assigned to the supplement group (which received 7.4 g of FOS as FDY) or the control group. At the beginning and end of the study, anthropometric measurements, blood sampling, clinical analyses and dietary intake were assessed. Results: A daily intake of FDY containing 7.4 g of FOS for 9 weeks was associated with a mean decrease in serum glucose ( p = 0.013), but supplementation did not reduce serum lipids in the study group. The administered dose did not adversely affect intestinal transit. It did not cause bloating, flatulence or intestinal discomfort. Conclusion: Freeze-dried powdered yacon is a good source of FOS, and daily consumption can have a favourable effect on serum glucose in the elderly. It is also practical, easy and safe to use and store. [ABSTRACT FROM AUTHOR]

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of amplified DNA fragment of the 16S and 23S rRNA genes was performed on 35 Helicobacter, 24 Campylobacter, and 15 Arcobacter strains. PCR amplification generated a 1004-bp fragment of 16S rDNA and a 2.6-Kbp fragment of 23S rDNA from each strain. The amplicons were digested with DdeI and HpaII, respectively. For both assays, distinctive profiles were obtained for each genus. 23S rDNA PCR-RFLP analysis with HpaII enzyme identified Campylobacter and Helicobacter strains at the species level. Analysis of 16S rRNA gene with DdeI enzyme was not useful for the specific identification of Campylobacter and Arcobacter, although it discriminated among Helicobacter species. The PCR-RFLP technique allowed for the discrimination among these three related genus with only one restriction enzyme; therefore it can be a simple, rapid, and useful method for routine identification. [ABSTRACT FROM AUTHOR]

Most communication networks are complex. In this paper, we address one of the fundamental problems we are facing nowadays, namely, how we can efficiently protect these networks. To this end, we study an immunization strategy and found that it works almost as good as targeted immunization, but using only local information about the network topology. Our findings are supported with numerical simulations of the Susceptible-Infected-Removed (SIR) model on top of real communication networks, where immune nodes are previously identified by a covering algorithm. The results provide useful hints in the way to designing and deploying a digital immune system. [ABSTRACT FROM AUTHOR]

Forecasting failure events is one of the most important problems in fracture mechanics and related sciences. In this paper, we use the Molchan scheme to investigate the error diagrams in a fracture model which has the notable advantage of displaying two completely different regimes according to the heterogeneity of the system. In one regime, a characteristic event is observed while for the second regime a power-law spectrum of avalanches is obtained reminiscent of self-organized criticality. We find that both regimes are different when predicting large avalanches and that, in the second regime, there are non-trivial temporal correlations associated to clustering of large events. Finally, we extend the discussion to seismology, where both kinds of avalanche size distributions can be seen. [ABSTRACT FROM AUTHOR]

: We study the spreading of a disease on top of structured scale-free networks recently introduced. By means of numerical simulations we analyze the SIS and the SIR models. Our results show that when the connectivity fluctuations of the network are unbounded whether the epidemic threshold exists strongly depends on the initial density of infected individuals and the type of epidemiological model considered. Analytical arguments are provided in order to account for the observed behavior. We conclude that the peculiar topological features of this network and the absence of small-world properties determine the dynamics of epidemic spreading. [ABSTRACT FROM AUTHOR]

We present a detailed analytical and numerical study for the spreading of infections with acquired immunity in complex population networks. We show that the large connectivity fluctuations usually found in these networks strengthen considerably the incidence of epidemic outbreaks. Scale-free networks, which are characterized by diverging connectivity fluctuations in the limit of a very large number of nodes, exhibit the lack of an epidemic threshold and always show a finite fraction of infected individuals. This particular weakness, observed also in models without immunity, defines a new epidemiological framework characterized by a highly heterogeneous response of the system to the introduction of infected individuals with different connectivity. The understanding of epidemics in complex networks might deliver new insights in the spread of information and diseases in biological and technological networks that often appear to be characterized by complex heterogeneous architectures. [ABSTRACT FROM AUTHOR]

We have studied the Mg doping of cubic GaN grown by plasma-assisted Molecular Beam Epitaxy (PA-MBE) over GaAs (001) substrates. In particular, we concentrated on conditions to obtain heavy p-type doping to achieve low resistance films which can be used in bipolar devices. We simulated the Mg-doped GaN transport properties by density functional theory (DFT) to compare with the experimental data. Mg-doped GaN cubic epitaxial layers grown under optimized conditions show a free hole carrier concentration with a maximum value of 6 × 1019 cm−3 and mobility of 3 cm2/Vs. Deep level transient spectroscopy shows the presence of a trap with an activation energy of 114 meV presumably associated with nitrogen vacancies, which could be the cause for the observed self-compensation behavior in heavily Mg-doped GaN involving Mg-VN complexes. Furthermore, valence band analysis by X-ray photoelectron spectroscopy and photoluminescence spectroscopy revealed an Mg ionization energy of about 100 meV, which agrees quite well with the value of 99.6 meV obtained by DFT. Our results show that the cubic phase is a suitable alternative to generate a high free hole carrier concentration for GaN. [ABSTRACT FROM AUTHOR]

We argue that theories and methods drawn from complexity science are urgently needed to guide the development and use of digital twins for cities. The theoretical framework from complexity science takes into account both the short-term and the long-term dynamics of cities and their interactions. This is the foundation for a new approach that treats cities not as large machines or logistic systems but as mutually interwoven self-organizing phenomena, which evolve, to an extent, like living systems., (© 2023. Springer Nature America, Inc.)

The objective of the present study was to establish the most suitable culture medium for the isolation of H. pylori from environmental and clinical samples. Ten different culture media were compared and evaluated. Four of them had been previously described and were modified in this study. The rest of the media were designed de novo. Three different matrices, tap water, wastewater, and feces, were inoculated with serial dilutions of H. pylori NCTC 11637 strain at a final concentration of 10 4 and 10 3  CFU/ml and the recovery rates were calculated. From inoculated tap water and wastewater samples, H. pylori colonies were recovered from four out of the analyzed culture media. When fecal samples were analyzed, the isolation of the pathogen under study was only possible from two culture media. Different optimal media were observed for each type of sample, even for wastewater and stool samples. Nevertheless, our results indicated that the combination of Dent Agar with polymyxin B sulfate did not inhibit the growth of H. pylori and was highly selective for its recovery, regardless of the sample origin. Thus, we propose the use of this medium as a diagnostic tool for the isolation of H. pylori from environmental and clinical samples, as well as for epidemiological studies.

A novel real-time PCR assay was developed for the direct detection in food of Helicobacter pullorum-like bacteria, which are occasionally associated with human enteric disease. Experiments using control strains showed that the realtime PCR assay was specific and reproducible, with a detection level of 1 colony-forming unit (CFU)/g. The assay was then applied to determine contamination rates in 30 samples of three types of chicken-meat products obtained from five retail outlets in Spain (Valencia); all of the samples were initially considered to be culture-negative for Helicobacter even after an enrichment period. H.pullorum-like DNA was detected in seven out of ten chicken carcasses and in one chicken-burger sample (without enrichment), as well as in one liver sample (after enrichment). Sequencing of three randomly selected PCR products confirmed concordance (99% homology) with the H. pullorum 16S rDNA gene. The advantages of real-time PCR over conventional PCR assays are the improved detection level, speed of testing, and validation of specificity by melting-point analysis. The fact that bacteria are frequently present in chicken carcasses sold in retail stores highlights the importance of more widely monitoring contamination rates. The novel assay described herein allows better assessment of potential human health risks posed by H. pullorum.