Search

Four industrial wastes, namely, tionite (T), iron grit (IG), electroplating sludge (ES), and mill scale (MS), are typically disposed of in controlled hazardous landfills because of their toxic content, posing potential harm to human health and to the environment. At the same time, the chemical composition of these wastes, specifically the nature and content of transition metals, makes them potentially attractive for reuse in pigments manufacturing. This work details the study of these residues for producing coloured perovskites to be tested as inorganic pigments. The residues were mixed, in different proportions, and subsequently calcined to produce the required structures. The colouring potential was then assessed in a ceramic paste and in a transparent glaze. Leaching tests were carried out to verify the effective immobilisation of the hazardous species. Dark pigments were successfully obtained from the mixtures of T: ES: Co3O4, T: MS and T: IG. The crystalline phases present in T: ES: Co3O4 are nickel–chromium iron oxide spinel–Fe1.5Cr0.5NiO4 (without Co) or trevorite–Fe2NiO4 (with Co), titanium nickel oxide–TiNiO3 and titanite–CaTiSiO5. The mixtures T: MS and T: IG presented hematite (Fe2O3) and pseudobrookite (Fe2TiO5). Leaching tests confirmed the non-hazardous or inert character of the synthesized pigments. Products showed brownish or greyish hues, depending on the pigment added. T:75ES_1100, T:73ES:2Co_1100, T:75MS_1000, T:75MS_1100 and T:75IG_1000 pigments can effectively and safely be used to colour ceramic paste replacing partially or totally the commercial pigments. [ABSTRACT FROM AUTHOR]

The Central and South‐Central Andes form a "two‐sided" mountain belt bounded by distinct zones of convergence in the forearc and backarc flanks. Previous geodetic interseismic deformation studies found that the forearc to backarc velocity field is better explained when elastic models allow reverse aseismic slip on the Andes eastern‐flank décollement faults. Here, we extend the earlier interpretation of interseismic motion and argue that normal aseismic creep of the Precordillera décollement is required to explain backarc Global Navigation Satellite System displacements during the co‐ and early postseismic phases of the 2015 Illapel, Chile, earthquake. This model significantly reduces the previously reported overlap between coseismic slip and afterslip on the megathrust of this earthquake, consistent with the expectation that these slip modes are spatially partitioned. These findings have direct implications for estimating recurrence interval and slip rate, and for probabilistic seismic hazard analysis on both sides of the orogen. Plain Language Summary: Between consecutive earthquakes in the Central and South‐Central Andes, during what is known as the interseismic phase, the traditional Nazca‐South America two‐plate model underpredicts the surface Global Navigation Satellite System (GNSS) velocities on the east side of the mountain belt. Previous studies show that adding an "Andean microplate," thus forming a three‐plate model, kinematically explains the observed velocity field on both sides of the Andes. We analyzed the GNSS coseismic displacements caused by the Mw 8.3 2015 Illapel, Chile, earthquake, and found that the traditional two‐plate model also underpredicts GNSS observations in the eastern side of the Andes. We show that adding the Andean microplate to the model, in the same manner as for the interseismic phase, and allowing aseismic slip on the detachment interface beneath it significantly reduces the observed surface displacements misfit. We also show that this holds for the displacements observed 50 days after the main shock, evidencing that the detachment geometry slips before, during, and after a large magnitude earthquake. Using the three‐plate model produces fault slip distributions that decrease overlap between local maxima in coseismic and aseismic slip, consistent with expectations from rate‐ and state‐dependent friction laws. Key Points: Revised co‐ and postseismic slip models account for forearc‐backarc coupling by allowing slip on the Argentine Precordillera décollementObserved continuous and survey Global Navigation Satellite System displacements on both sides of the Andes are better explained by models with a décollementAdding a décollement significantly reduces megathrust coseismic slip and afterslip overlap, compatible with rate and state friction law [ABSTRACT FROM AUTHOR]

Trees' functional strategies to cope with extreme drought are essential under climate change. In a mixed Mediterranean forest, we analyzed the functional strategy in response to drought of four co‐occurring species (Pinus pinea, Pinus pinaster, Juniperus oxycedrus, and Quercus ilex) during two years. Specifically, we assessed functional traits related to tree water status, leaf water relations, and gas exchange. Different trait‐syndrome metrics and the functional strategies under water stress observed suggested a species drought‐tolerance differentiation, with the more anysohidric Q. ilex and J. oxycedrus showing a much higher drought tolerance than the more isohydric P. pinea and P. pinaster. All species recovered from negative leaf turgor reached during peak water stress in summer. Q. ilex and J. oxycedrus kept lower leaf osmotic potentials and lower sensitivity of leaf gas exchange and leaf photochemistry to water stress. In contrast, the pine species exhibited more drought‐avoidant and water‐conservative strategies, yet this behavior was less effective in mitigating water stress's impact on their physiology. The pine species were the most affected by drought, with prolonged near‐zero net photosynthesis during summer. P. pinaster was more isohydric than P. pinea and exhibited a lower capacity to maintain leaf turgor. Physiological processes regulating leaf turgor under drought constitute a key functional strategy involved in the carbon and water‐related mechanisms, ultimately inducing mortality under hot drought. The currently observed mortality dynamics for P. pinaster, and to a lower extent in P. pinea, may be exacerbated by loss of functional homeostasis. [ABSTRACT FROM AUTHOR]

Objective: To compare the predictive performance of three different mathematical models for first‐trimester screening of pre‐eclampsia (PE), which combine maternal risk factors with mean arterial pressure (MAP), uterine artery pulsatility index (UtA‐PI) and serum placental growth factor (PlGF), and two risk‐scoring systems. Methods: This was a prospective cohort study performed in eight fetal medicine units in five different regions of Spain between September 2017 and December 2019. All pregnant women with singleton pregnancy and a non‐malformed live fetus attending their routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation were invited to participate in the study. Maternal characteristics and medical history were recorded and measurements of MAP, UtA‐PI, serum PlGF and pregnancy‐associated plasma protein‐A (PAPP‐A) were converted into multiples of the median (MoM). Risks for term PE, preterm PE (< 37 weeks' gestation) and early PE (< 34 weeks' gestation) were calculated according to the FMF competing‐risks model, the Crovetto et al. logistic regression model and the Serra et al. Gaussian model. PE classification was also performed based on the recommendations of the National Institute for Health and Care Excellence (NICE) and the American College of Obstetricians and Gynecologists (ACOG). We estimated detection rates (DR) with their 95% CIs at a fixed 10% screen‐positive rate (SPR), as well as the area under the receiver‐operating‐characteristics curve (AUC) for preterm PE, early PE and all PE for the three mathematical models. For the scoring systems, we calculated DR and SPR. Risk calibration was also assessed. Results: The study population comprised 10 110 singleton pregnancies, including 32 (0.3%) that developed early PE, 72 (0.7%) that developed preterm PE and 230 (2.3%) with any PE. At a fixed 10% SPR, the FMF, Crovetto et al. and Serra et al. models detected 82.7% (95% CI, 69.6–95.8%), 73.8% (95% CI, 58.7–88.9%) and 79.8% (95% CI, 66.1–93.5%) of early PE; 72.7% (95% CI, 62.9–82.6%), 69.2% (95% CI, 58.8–79.6%) and 74.1% (95% CI, 64.2–83.9%) of preterm PE; and 55.1% (95% CI, 48.8–61.4%), 47.1% (95% CI, 40.6–53.5%) and 53.9% (95% CI, 47.4–60.4%) of all PE, respectively. The best correlation between predicted and observed cases was achieved by the FMF model, with an AUC of 0.911 (95% CI, 0.879–0.943), a slope of 0.983 (95% CI, 0.846–1.120) and an intercept of 0.154 (95% CI, –0.091 to 0.397). The NICE criteria identified 46.7% (95% CI, 35.3–58.0%) of preterm PE at 11% SPR and ACOG criteria identified 65.9% (95% CI, 55.4–76.4%) of preterm PE at 33.8% SPR. Conclusions: The best performance of screening for preterm PE is achieved by mathematical models that combine maternal factors with MAP, UtA‐PI and PlGF, as compared to risk‐scoring systems such as those of NICE and ACOG. While all three algorithms show similar results in terms of overall prediction, the FMF model showed the best performance at an individual level. © 2024 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Solar partially ionized plasma is frequently modelled using single-fluid (1F) or two-fluid (2F) approaches. In the 1F case, charge-neutral interactions are often described through ambipolar diffusion, while the 2F model fully considers charge-neutral drifts. Here, we expand the definition of the ambipolar diffusion coefficient to include inelastic collisions (ion/rec) in two cases: a VAL3C one-dimensional model and a 2F simulation of the Rayleigh–Taylor instability (RTI) in a solar prominence thread based on [Lukin et al. 2024 Phil. Trans. R. Soc. A382, 20230417. (doi:10.1098/rsta.2023.0417)]. On one side, we evaluate the relative importance of the inelastic contribution, compared to elastic and charge-exchange collisions. On the other side, we compare the contributions of ion/rec, thermal pressure, viscosity and magnetic forces to the charge-neutral drift velocity of the turbulent flow of the RTI. Our analysis reveals that the contribution of inelastic collisions to the ambipolar diffusion coefficient is negligible across the chromosphere, allowing the classical definition of this coefficient to be safely used in 1F modelling. However, in the transition region, the contribution of inelastic collisions can become as significant as that of elastic collisions. Furthermore, we ascertain that the thermal pressure force predominantly influences the charge-neutral drifts in the RTI model, surpassing the impact of the magnetic force. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'. [ABSTRACT FROM AUTHOR]

Background: During perinatal period, the immune system of calves is developing, making them vulnerable to infectious diseases that affect their growth or increasing mortality. Phytobiotics have various physiological effects on animals that could improve their performance and health. In this study, the effect of a feed herbal mixture made from Azadirachta indica and Phyllanthus niruri were evaluated in dairy calves. Methods: Forty Holstein calves were assigned into four groups (doses of 0, 2, 3 and 4 g d-1) and productive and health parameters were recorded. Results were analyzed according to a completely randomized design in which linear and quadratic effects of daily feed additive dose were tested. Result: Increasing the dose of herbal mixture linearly reduced final body weight, body weight gain and daily calve starter intake, although it improved feed conversion. Blood tests showed that hematocrit and hemoglobin increased quadratically. The number of segmented neutrophils increased linearly. Finally, the number of pneumonia cases decreased quadratically. These results suggest that supplementation with herbal additives could improve feed efficiency and improve the health status of calves. [ABSTRACT FROM AUTHOR]

The growing interest in anaerobic digestion has led to an increase in the production of digestate that can be re-used. This work evaluates the possibility of using black soldier fly larvae (BSFL) to valorize biogas digestate, maize residue and alfalfa. The solid fraction of two digestates originating from two different biogas plants was used. Different diets (mixed or single substrates) were developed using digestate, maize residue and alfalfa. In addition, thermal hydrolysis as well as enzymatic hydrolysis were performed on the agricultural crops to break down fibers into reducing sugars, before being fed to BSFL. Chemical analysis of the substrates and a performance analysis were conducted. Application of the pretreatment on the agricultural crops improved larval growth on maize residue and alfalfa. Although larvae reached higher mass gain on pretreated maize residue and alfalfa than on non-pretreated crops, once these agricultural crops were mixed with digestate, performance decreased. Indeed, larval growth on digestate-based diets was very poor compared to the standard diet, with the average individual larval weight reared on digestate 1 and digestate 2 being 14.6 ± 2.54 mg and 46.43 ± 6.68 mg, respectively. A significant difference (p = 0.0018) was found between length gain of the two digestates, indicating that certain digestates lead to different BSFL yield. According to the results of this study, BSFL treatment of digestate was not efficient and further research is needed to elucidate the mechanisms preventing digestate from being effectively converted into larval biomass. [ABSTRACT FROM AUTHOR]

This work proposes a methodology that combines distributed and lumped models to simulate the current distribution within an indirect heat resistance furnace and, in particular, to calculate the current to be supplied for achieving a desired power output. The distributed model is a time-harmonic eddy current problem, which is solved numerically using the finite element method. The lumped model relies on calculating a reduced impedance associated with an equivalent circuit model. Numerical simulations and plant measurements demonstrate the effectiveness of this approach. The good correlation between the results indicates that this approximation is well-suited to support the design and improve the efficiency of the furnace in a short time. [ABSTRACT FROM AUTHOR]

The Mancha3D code is a versatile tool for numerical simulations of magnetohydrodynamic (MHD) processes in solar/stellar atmospheres. The code includes nonideal physics derived from plasma partial ionization, a realistic equation of state and radiative transfer, which allows performing high-quality realistic simulations of magnetoconvection, as well as idealized simulations of particular processes, such as wave propagation, instabilities or energetic events. The paper summarizes the equations and methods used in the Mancha3D (Multifluid (-purpose -physics -dimensional) Advanced Non-ideal MHD Code for High resolution simulations in Astrophysics 3D) code. It also describes its numerical stability and parallel performance and efficiency. The code is based on a finite difference discretization and a memory-saving Runge–Kutta (RK) scheme. It handles nonideal effects through super-time-stepping and Hall diffusion schemes, and takes into account thermal conduction by solving an additional hyperbolic equation for the heat flux. The code is easily configurable to perform different kinds of simulations. Several examples of the code usage are given. It is demonstrated that splitting variables into equilibrium and perturbation parts is essential for simulations of wave propagation in a static background. A perfectly matched layer (PML) boundary condition built into the code greatly facilitates a nonreflective open boundary implementation. Spatial filtering is an important numerical remedy to eliminate grid-size perturbations enhancing the code stability. Parallel performance analysis reveals that the code is strongly memory bound, which is a natural consequence of the numerical techniques used, such as split variables and PML boundary conditions. Both strong and weak scalings show adequate performance up to several thousands of processors (CPUs). [ABSTRACT FROM AUTHOR]

Supernova remnants are the nebular leftover of defunct stellar environments, resulting from the interaction between a supernova blastwave and the circumstellar medium shaped by the progenitor throughout its life. They display a large variety of non-spherical morphologies such as ears that shine non-thermally. We have modelled the structure and the non-thermal emission of the supernova remnant G1.9 + 0.3 through 3D magnetohydrodynamic numerical simulations. We propose that the peculiar ear-shaped morphology of this supernova remnant results from the interaction of its blast wave with a magnetized circumstellar medium, which was previously asymmetrically shaped by the past stellar wind emanating from the progenitor star or its stellar companion. We created synthetic non-thermal radio and X-ray maps from our simulated remnant structure, which are in qualitative agreement with observations, forming ears on the polar directions. Our synthetic map study explains the discrepancies between the measured non-thermal radio and X-ray surface brightness distributions assuming that the inverse Compton process produces the observed X-ray emission. [ABSTRACT FROM AUTHOR]

Objective: Effective first‐trimester screening for pre‐eclampsia (PE) can be achieved using a competing‐risks model that combines risk factors from the maternal history with multiples of the median (MoM) values of biomarkers. A new model using artificial intelligence through machine‐learning methods has been shown to achieve similar screening performance without the need for conversion of raw data of biomarkers into MoM. This study aimed to investigate whether this model can be used across populations without specific adaptations. Methods: Previously, a machine‐learning model derived with the use of a fully connected neural network for first‐trimester prediction of early (< 34 weeks), preterm (< 37 weeks) and all PE was developed and tested in a cohort of pregnant women in the UK. The model was based on maternal risk factors and mean arterial blood pressure (MAP), uterine artery pulsatility index (UtA‐PI), placental growth factor (PlGF) and pregnancy‐associated plasma protein‐A (PAPP‐A). In this study, the model was applied to a dataset of 10 110 singleton pregnancies examined in Spain who participated in the first‐trimester PE validation (PREVAL) study, in which first‐trimester screening for PE was carried out using the Fetal Medicine Foundation (FMF) competing‐risks model. The performance of screening was assessed by examining the area under the receiver‐operating‐characteristics curve (AUC) and detection rate (DR) at a 10% screen‐positive rate (SPR). These indices were compared with those derived from the application of the FMF competing‐risks model. The performance of screening was poor if no adjustment was made for the analyzer used to measure PlGF, which was different in the UK and Spain. Therefore, adjustment for the analyzer used was performed using simple linear regression. Results: The DRs at 10% SPR for early, preterm and all PE with the machine‐learning model were 84.4% (95% CI, 67.2–94.7%), 77.8% (95% CI, 66.4–86.7%) and 55.7% (95% CI, 49.0–62.2%), respectively, with the corresponding AUCs of 0.920 (95% CI, 0.864–0.975), 0.913 (95% CI, 0.882–0.944) and 0.846 (95% CI, 0.820–0.872). This performance was achieved with the use of three of the biomarkers (MAP, UtA‐PI and PlGF); inclusion of PAPP‐A did not provide significant improvement in DR. The machine‐learning model had similar performance to that achieved by the FMF competing‐risks model (DR at 10% SPR, 82.7% (95% CI, 69.6–95.8%) for early PE, 72.7% (95% CI, 62.9–82.6%) for preterm PE and 55.1% (95% CI, 48.8–61.4%) for all PE) without requiring specific adaptations to the population. Conclusions: A machine‐learning model for first‐trimester prediction of PE based on a neural network provides effective screening for PE that can be applied in different populations. However, before doing so, it is essential to make adjustments for the analyzer used for biochemical testing. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Copyright of Panorama Económico is the property of Universidad de Cartagena and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We address the Sobolev–Neumann problem for the bi-harmonic equation describing the bending of the Kirchhoff plate with a traction-free edge but fixed at two rows of points. The first row is composed of points placed at the edge, at a small distance ε > 0 between them, and the second one is composed of points placed along a contour at distance O(ε1+α) from the edge. We prove that in the case where α ∈ [0, 1/2), the limit passage as ε → +0 leads to the plate rigidly clamped along the edge while, in the case where α > 1/2, under additional conditions, the limit boundary conditions become of the hinge support type. Based on the asymptotic analysis of the boundary layer in a similar problem, we predict that in the critical case α = 1/2, the boundary hinge-support conditions with friction occur in the limit. We discuss the available generalization of the results and open questions. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the diagnostic accuracy of the Fetal Medicine Foundation (FMF) competing‐risks model, incorporating maternal characteristics, mean arterial pressure (MAP), uterine artery pulsatility index (UtA‐PI) and placental growth factor (PlGF) (the 'triple test'), for the prediction at 11–13 weeks' gestation of preterm pre‐eclampsia (PE) in a Spanish population. Methods: This was a prospective cohort study performed in eight fetal medicine units in five different regions of Spain between September 2017 and December 2019. All pregnant women with a singleton pregnancy and a non‐malformed live fetus attending a routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation were invited to participate. Maternal demographic characteristics and medical history were recorded and MAP, UtA‐PI, serum PlGF and pregnancy‐associated plasma protein‐A (PAPP‐A) were measured following standardized protocols. Treatment with aspirin during pregnancy was also recorded. Raw values of biomarkers were converted into multiples of the median (MoM), and audits were performed periodically to provide regular feedback to operators and laboratories. Patient‐specific risks for term and preterm PE were calculated according to the FMF competing‐risks model, blinded to pregnancy outcome. The performance of screening for PE, taking into account aspirin use, was assessed by calculating the area under the receiver‐operating‐characteristics curve (AUC) and detection rate (DR) at a 10% fixed screen‐positive rate (SPR). Risk calibration of the model was assessed. Results: The study population comprised 10 110 singleton pregnancies, including 72 (0.7%) that developed preterm PE. In the preterm PE group, compared to those without PE, median MAP MoM and UtA‐PI MoM were significantly higher, and median serum PlGF MoM and PAPP‐A MoM were significantly lower. In women with PE, the deviation from normal in all biomarkers was inversely related to gestational age at delivery. Screening for preterm PE by a combination of maternal characteristics and medical history with MAP, UtA‐PI and PlGF had a DR, at 10% SPR, of 72.7% (95% CI, 62.9–82.6%). An alternative strategy of replacing PlGF with PAPP‐A in the triple test was associated with poorer screening performance for preterm PE, giving a DR of 66.5% (95% CI, 55.8–77.2%). The calibration plot showed good agreement between predicted risk and observed incidence of preterm PE, with a slope of 0.983 (95% CI, 0.846–1.120) and an intercept of 0.154 (95% CI, −0.091 to 0.397). Conclusions: The FMF model is effective in predicting preterm PE in the Spanish population at 11–13 weeks' gestation. This method of screening is feasible to implement in routine clinical practice, but it should be accompanied by a robust audit and monitoring system, in order to maintain high‐quality screening. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

The flavor-violating decay of a new neutral massive gauge boson Z ′ → μ e is analyzed in the context of extended models, in which this particle emerges. By means of the analysis of the μ → e γ decay, μ - e conversion process in nuclei and the μ → e e + e - decay, the strength of the Z ′ μ e coupling is estimated and used to calculate the branching ratio of the Z ′ → μ e decay. This is done for the so-called Z S , Z LR , Z χ , Z ψ and Z η bosons. We found that, through the μ - e conversion process, the most restrictive bound for the coupling is provided by the Z LR boson. Meanwhile, by means of the μ → e e + e - decay, the most restrictive bound for the Z ′ μ e coupling is provided by the Z χ boson. However, if we concentrate on the less restrictive prediction for the Br( Z ′ → μ e ), this comes from the Z η boson and the resulting branching ratio is less than 10 - 4 . On the other hand, if we consider the most restrictive bound, the branching ratio for the process is below 2 × 10 - 7 , which results from the Z RL boson, and is obtained through the μ - e conversion process. [ABSTRACT FROM AUTHOR]

The braking system is the most important element in the automotive industry because it reduces the speed through the friction between the brake disc and the pad, transforming the kinetic energy into thermal due to the wear generated on both surfaces during motion. This works aims to design a tribological machine for Francisco de Paula Santander Ocaña University, applying the design theories to obtain a device with the customer's engineering requirements. Also, Solidworks software was used to obtain a conceptual model and structural analysis of the main components of the machine to guarantee the correct behavior during operation. The results exposed that the structure and calypter holder elaborated of ASTM A36 steel support stresses less than 1.0 MPa considering a good material selection, geometrical design, and conceptual model selected of the machine operation, with high levels of the security factor (more than 10). [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Facultad de Medicina Veterinaria y de Zootecnia is the property of Revista de la Facultad de Medicina Veterinaria y de Zootecnia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de la Facultad de Medicina Veterinaria y de Zootecnia is the property of Revista de la Facultad de Medicina Veterinaria y de Zootecnia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Preschool teachers can become attachment figures that complement the children's families of origin, becoming relevant actors in their early development. This article presents the results of a group video feedback program on early childhood teachers in public centers. The model, which focuses on promoting "educational sensitivity", comprises 5 group sessions. A pre-post evaluation of 157 participants was conducted by coding dyad and group interaction videos. After the intervention, a significant increase relative to the baseline was found in measures of dyad (d = 0.67) and group sensitivity (d = 0.13), among other positive outcomes. Likewise, a significant association was found between variables of dyadic sensitivity and group sensitivity, concurrently and prospectively. The promising results obtained support the viability of the model in early education. Future studies should include a control group and randomization measures to strengthen these conclusions and incorporate a follow-up component to evaluate the program's long-term impact on educators. [ABSTRACT FROM AUTHOR]

Copyright of Magazine of the Colombian Association of Biological Sciences / Revista de la Asociación Colombiana de Ciencias Biológicas (ACCB) is the property of Magazine of the Colombian Association of Biological Sciences (ACCB) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We consider a homogenization problem for the Laplace operator posed in a bounded domain of the upper half-space, a part of its boundary being in contact with the plane { x 3 = 0 } . On this part, the boundary conditions alternate from Neumann to nonlinear-Robin, being of Dirichlet type outside. The nonlinear-Robin boundary conditions are imposed on small regions periodically placed along the plane and contain a Robin parameter that can be very large. We provide all the possible homogenized problems, depending on the relations between the three parameters: period ε , size of the small regions r ε and Robin parameter β (ε) . In particular, we address the convergence, as ε tends to zero, of the solutions for the critical size of the small regions r ε = O (ε 2) . For certain β (ε) , a nonlinear capacity term arises in the strange term which depends on the macroscopic variable and allows us to extend the usual capacity definition to semilinear boundary conditions. [ABSTRACT FROM AUTHOR]

In mountain areas, the phenology and productivity of grassland are closely related to snow dynamics. However, the influence that snow melt timing has on grassland growing still needs further attention for a full understanding, particularly at high spatial resolution. Aiming to reduce this knowledge gap, this work exploits 1 m resolution snow depth and Normalized Difference Vegetation Index observations acquired with an Unmanned Aerial Vehicle at a sub-alpine site in the Pyrenees. During two snow seasons (2019–2020 and 2020–2021), 14 NDVI and 17 snow depth distributions were acquired over 48 ha. Despite the snow dynamics being different in the two seasons, the response of grasslands greening to snow melt-out exhibited a very similar pattern in both. The NDVI temporal evolution in areas with distinct melt-out dates reveals that sectors where the melt-out date occurs in late April or early May (optimum melt-out) reach the maximum vegetation productivity. Zones with an earlier or a later melt-out rarely reach peak NDVI values. The results obtained in this study area, suggest that knowledge about snow depth distribution is not needed to understand NDVI grassland dynamics. The analysis did not reveal a clear link between the spatial variability in snow duration and the diversity and richness of grassland communities within the study area. [ABSTRACT FROM AUTHOR]

In mountain areas, the phenology and productivity of grassland are closely related to snow dynamics. However, the influence that snow melt timing has on grassland growing still needs further attention for a full understanding, particularly at high spatial resolution. Aiming to reduce this knowledge gap, this work exploits 1 m resolution snow depth and Normalized Difference Vegetation Index observations acquired with an Unmanned Aerial Vehicle at a sub-alpine site in the Pyrenees. During two snow seasons (2019–2020 and 2020–2021), 14 NDVI and 17 snow depth distributions were acquired over 48 ha. Despite the snow dynamics being different in the two seasons, the response of grasslands greening to snow melt-out exhibited a very similar pattern in both. The NDVI temporal evolution in areas with distinct melt-out dates reveals that sectors where the melt-out date occurs in late April or early May (optimum melt-out) reach the maximum vegetation productivity. Zones with an earlier or a later melt-out rarely reach peak NDVI values. The results obtained in this study area, suggest that knowledge about snow depth distribution is not needed to understand NDVI grassland dynamics. The analysis did not reveal a clear link between the spatial variability in snow duration and the diversity and richness of grassland communities within the study area. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to identify the risk factors associated with house infestation by Triatomadimidiata as well as with Trypanosomacruzi infection in humans and owned dogs in two rural communities from the municipality of Catemaco, Veracruz, Mexico. Methods: One hundred and 16 human blood samples and 34 dog blood samples were collected. The presence of anti-T. cruzi antibodies was determined using four different ELISA assays. Moreover, reactive ELISA sera from humans and dogs were processed by indirect immunofluorescence (IFI) to confirm the presence of anti-T. cruzi antibodies. Results: Serologic tests for T. cruzi infection showed a prevalence of 5.1% (6/116) in humans and of 50% (17/34) in owned dogs. Conclusion: The presence of animals (dogs, chickens and wild animals), as well as some characteristics of house construction were identified as risk factors for infestation and infection. Complementary studies must be carried out to allow a better understanding of the transmission dynamics in the state of Veracruz, Mexico, and the implementation of adequate control programs. [ABSTRACT FROM AUTHOR]

Unplanned hospital readmission is a problem that affects hospitals worldwide and is due to different factors. The identification of those factors can help determine which patients are at greater risk of hospital readmission for early intervention. Our end goal is to predict and identify patterns to (i) feed a decision support system for efficient management of patients and resources and (ii) detect patients at high risk of 30-days readmission enabling preventive actions to improve management of hospital discharges. This study aims to analyze whether natural language processing and specifically keyword extractions tools and sentiment analysis can support 30-days readmission prediction. Features extracted from medical history notes and discharge reports were used to train a Logistic Regression model. The resulting model obtains an AUC of 0.63 indicating that the sentiment polarity score of the discharge report and several of the extracted keywords are representative features to consider. [ABSTRACT FROM AUTHOR]

Megabenthic communities on continental margins benefit from structural complexity of the seafloor and sedimentary dynamics. These communities were tested in the outer margins of the Yucatan continental shelf (YCS) during August 2016 to evaluate the relationships between community attributes with environmental variables. The total capture was 1,366 103 ind km−2 and 2,078 kg ash free dry weight (AFDW) km−2, distributed among 319 species. Crustaceans and molluscs were co-dominant in abundance (576,629 ind km−2 ∼42.2% and 481,372 ind km−2 ∼35.2%), while crustaceans and sponges were the greatest contributors to community biomass (699.84 kg AFDW km−2 ∼33.6% and 47.8 kg AFDW km−2 ∼23.0%). Local diversity was higher than reported for other areas of the GoM, showing a pseudo-latitudinal gradient of richness related to the karstic bottom and autogenic species. Beta diversity showed no species loss in these communities. The BIOENV test pointed to longitude, temperature, sorting, vanadium, 2.6-dimethyl naphthalene, latitude, chlorophyll, average grain size, n-C16 and n-C23 as the most important variables. Hydrocarbons were recorded at lower concentrations than the threshold effects level (TEL) reference values; however, the significant correlation between richness and dibenzothiophene must be evaluated. Beta diversity exhibited a high turnover and functional diversity showed an absence of regional distribution. Differences in benthic megafauna among sites were because of gradients in latitude and concentrations of aliphatic compounds which can be attributed to the distance from the stations to the coastline or groundwater flow. Environmental monitoring programmes are recommended because of petrogenic compounds that influence the community structure. [ABSTRACT FROM AUTHOR]

We consider the following repulsive-productive chemotaxis model: find u ≥ 0, the cell density, and v ≥ 0, the chemical concentration, satisfying 1 ∂ t u − Δ u − ∇ ⋅ (u ∇ v) = 0 in Ω , t > 0 , ∂ t v − Δ v + v = u p i n Ω , t > 0 , with p ∈ (1, 2), Ω ⊆ ℝ d a bounded domain (d = 1, 2, 3), endowed with non-flux boundary conditions. By using a regularization technique, we prove the existence of global in time weak solutions of (1) which is regular and unique for d = 1, 2. Moreover, we propose two fully discrete Finite Element (FE) nonlinear schemes, the first one defined in the variables (u,v) under structured meshes, and the second one by using the auxiliary variable σ = ∇v and defined in general meshes. We prove some unconditional properties for both schemes, such as mass-conservation, solvability, energy-stability and approximated positivity. Finally, we compare the behavior of these schemes with respect to the classical FE backward Euler scheme throughout several numerical simulations and give some conclusions. [ABSTRACT FROM AUTHOR]

To perform an asymptotic analysis of spectra of singularly perturbed periodic waveguides, it is required to estimate remainders of asymptotic expansions of eigenvalues of a model problem on the periodicity cell uniformly with respect to the Floquet parameter. We propose two approaches to this problem. The first is based on the max–min principle and is sufficiently easily realized, but has a restricted application area. The second is more universal, but technically complex since it is required to prove the unique solvability of the problem on the cell for some value of the spectral parameter and the Floquet parameter in a nonempty closed segment, which is verified by constructing an almost inverse operator of the operator of an inhomogeneous model problem in variational setting. We consider boundary value problems on the simplest periodicity cell: a rectangle with a row of fine holes. [ABSTRACT FROM AUTHOR]

We calculate bounds for the branching ratio of the B s 0 → τ e decay, for the first time, in the context of flavor changing neutral currents mediated by a Z ′ gauge boson, which can arise from five extended models. In this sense, by using experimental measurements on the B → X s γ decay and the B s 0 → μ + μ − process, we look for constraints of the Z ′ b s coupling, where the more restrictive bound is offered by the last one. On the other hand, by employing the experimental restriction on the τ → e e ē decay, the strength of the Z ′ τ e coupling is estimated. Our analysis is based on the more recent experimental results on searches for the Z ′ gauge boson in ATLAS and CMS detectors. In addition, we revisited the B s 0 → τ μ , μ e meson decays by using different approaches not previously reported. The strengths of the Z ′ τ μ and Z ′ μ e couplings were estimated by employing experimental restrictions on the τ → μ μ μ ̄ decay and the μ − e conversion rate, respectively. Thus, we predict the following upper bounds: B s 0 → τ e ∼ 1 0 − 6 , B s 0 → τ μ ∼ 1 0 − 6 and B s 0 → μ e ∼ 1 0 − 1 1 . [ABSTRACT FROM AUTHOR]

Gas scrubbing sludge (SS) and fine dust of converters (SC) are wastes generated in the off-gas cleaning system of smelting and converting processes. Both wastes are considered hazardous materials due to their high metal contents and leaching characteristics. The main purpose of this study was to gain essential knowledge on the recovery of valuable elements contained in these wastes. Thus, an exhaustive characterization was carried out to determine the composition, mineral phases, particle size, and leachability of both wastes (SS and SC) as a preliminary step to select the most appropriate applications and treatment for them. These wastes are composed of fine particles (~ 95% < 63 µm), mainly containing Pb (> 20%) as anglesite (PbSO4), while SS presents a high concentration of Se (34%), which is mainly identified as metallic selenium. Therefore, these residues could be used as secondary sources of Pb and Se. The recovery of Se by roasting process and Pb recovery by hydrometallurgical route seem to be the best options for the management of these wastes. [ABSTRACT FROM AUTHOR]

Campylobacter fetus subsp. fetus is the causal agent of sporadic abortion and infertility in bovines that produces economic losses in livestock. Aims: This study evaluates the capability of C. fetus subsp. fetus to invade and survive in bovine endometrial epithelial cells and attempts to describe a pathogenic mechanism of this microorganism. Methods: Primary culture of bovine endometrial epithelial cells was challenged with C. fetus subsp. fetus. Intracellular bacteria, represented by the number of genomic copies (g.c.) were quantified at 0, 2, 4, 10, and 24 hours post-infection (h.p.i.), by quantitative polymerase chain reaction (qPCR). The presence of intracellular bacteria was evaluated by immunofluorescence and immunohistochemistry. Results: The results showed that only viable C. fetus subsp. fetus could invade endometrial cells. The g.c. number in assays with viable C. fetus subsp. fetus reached an average value of 656 g.c., remained constant until 4 h.p.i., then decreased to 100 g.c, at 24 h.p.i. In assays with non-viable microorganisms, the average value of g.c. was less than 1 g.c. and never changed. The intracellular presence of this bacteria was confirmed at 2 h.p.i. by immunofluorescence and immunohistochemistry. Conclusion: The results suggest that only C. fetus subsp. fetus viable can invade bovine endometrial epithelial cells but will not replicate in them, indicating that the endometrial cells do not represent a replication niche for this pathogen. Nonetheless, this invasion capability suggests that this type of cell could be employed by the pathogen to spread to other tissues. [ABSTRACT FROM AUTHOR]

The rare top quark decays mediated by a new neutral massive gauge boson that is predicted in models with extended gauge symmetries are studied. We focus on the processes t → c V , u V induced at the one loop level, where V = γ , g , by considering different extended models. It is found that, within a broad range of mass of the new neutral gauge boson, the models predict branching ratios for the decays in study that are competitive with respect to the corresponding branching ratios in the Standard Model (SM). In order to establish bound on our branching ratios, we consider the recent experimental bounds as m Z ′ ≥ 3. 8 – 4. 5 TeV , depending on the model, which also impose restrictions on our calculation. Even in this case, the resulting branching ratios are of the same order of magnitude as that predicted by the SM. It should be noted that for the case of two models studied here, since no experimental bound exists to compare with, the results could be important, as they are, in the best of cases, two orders of magnitude larger than the predicted by the SM. [ABSTRACT FROM AUTHOR]

Purpose: The state of Puebla has the social marginalization and ecological conditions for the transmission of infectious agents to be effective. Until a few years ago, the state of Puebla was considered non-endemic to the presence of Trypanosoma cruzi as there are no official reports of chronic cases. The objective of this work was to carry out a preliminary study on the prevalence of anti-T. cruzi antibodies in rural areas of the Huatlatlauca municipality in the Mixtec sierra of the state of Puebla. Methods: A total of 196 serum samples from 12 rural localities were tested by using four tests: two enzyme-linked immunosorbent assays, an xenodiagnoses and PCR assay. Results: Overall, 28 (14.2%) of 196 samples were positive for T. cruzi by ≥ 2 tests (95% CI 6.6–20.8%). Our results suggested that the municipality of Huatlatlauca in the Mixteca Sierra of the state of Puebla is an area with endemic potential for the disease with a high prevalence rate in the adult population and with cases in newborns, these high transmission rates are probably associated with problems of congenital and vector transmission. Conclusion: Additional studies should be conducted to generate adequate campaigns for the control of Chagas disease in this area. [ABSTRACT FROM AUTHOR]

We performed three-dimensional magnetohydrodynamic simulations to study the evolution of a supernova remnant (SNR) in a turbulent neutral atomic interstellar medium. The media used as background shares characteristics with the Solar neighbourhood and the SNR has mass and energy similar to those of a Type Ia object. Our initial conditions consist of dense clouds in a diluted medium, with the main difference between simulations being the average magnitude of the magnetic field. We measured amplifications of the magnetic energy of up to 34  |${{\rm per\ cent}}$|⁠ , and we generated synthetic maps that illustrate how the same object can show different apparent geometries and physical properties when observed through different lines of sight. [ABSTRACT FROM AUTHOR]

Objectives: The aims of this study were (i) to examine the independent associations of the time spent in daily activities measured by multi-sensor pattern-recognition with frailty and physical functioning (PF); and (ii) to analyze how relocating time between these daily activities is associated with frailty and PF in a sample of older adults. Design: Cross-sectional study. Setting and participants: The study sample consists of 436 (287 women) high-functioning community-dwelling older adults, aged 65 to 92 years, who participated in the IMPACT65+ Study. Measurements: Frailty was calculated as a continuous measure; based on the five widely recognized Fried's criteria. PF was assessed using the SF-12 questionnaire. The time in daily activities was assessed by the Intelligent Device for Energy expenditure and Activity (IDEEA). Independent associations of daily activities with frailty and PF were examined using linear regression models adjusting for potential confounders. The isotemporal substitution models for estimate the effect of replacing time in one activity with the same amount of time in another activity while holding wake time constant. Results: Time spent lying was directly associated, while time in walk at average and brisk pace was inversely associated with frailty. The independent associations for PF were similar to lying, walk at average pace and walk at brisk pace. Isotemporal substitution analyses revealed a clear beneficial effect of hypothetically replacing 30 min/day of sedentary behaviors or light physical activity by the same amount of moderate-to-vigorous physical activity for frailty and PF. Conclusion: This is the first study examining the activity-specific and isotemporal association of daily activities with frailty and PF in older adults. Isotemporal substitution analyses showed that replacing sedentary behaviors (lie, recline, passive sit) by light-intensity activities (active sit, stand and walk at slow pace), as well as light-intensity activities by activities at MVPA such as walk at brisk pace, may produce theoretical improvements in frailty and PF. These findings are important for the development of effective interventions focused on reducing age-related frailty and declines in PF. [ABSTRACT FROM AUTHOR]

Recess is a frequent target in school-based physical activity (PA) promotion research but there are challenges in assessing PA during this time period. The purpose of this study was to evaluate the reliability and validity of a recess PA recall (RPAR) instrument designed to assess total PA and time spent in moderate to vigorous PA (MVPA) during recess. One hundred twenty-five 7th and 8th-grade students (59 females), age 12-14 years, participated in the study. Activity levels were objectively monitored on Mondays using different activity monitors (Yamax Digiwalker, Biotrainer and ActiGraph). On Tuesdays, 2 RPAR self-reports were administered within 1-hr. Test-retest reliability showed ICC = 0.87 and 0.88 for total PA and time spent in MVPA, respectively. The RPAR was correlated against Yamax (r = .35), Biotrainer (r = .40 and 0.54) and ActiGraph (r = .42) to assess total PA during recess. The RPAR was also correlated against ActiGraph (r = .54) to assess time spent in MVPA during recess. Mean difference between the RPAR and ActiGraph to assess time spent in MVPA during recess was no significant (2.15 } 3.67 min, p = .313). The RPAR showed an adequate reliability and a reasonable validity for assessing PA during the school recess in youth. [ABSTRACT FROM AUTHOR]

The use of metal stripes for the guiding of plasmons is a well established technique for the infrared regime and has resulted in the development of a myriad of passive optical components and sensing devices. However, the plasmons suffer from large losses around sharp bends, making the compact design of nanoscale sensors and circuits problematic. A compact alternative would be to use evanescent coupling between two sufficiently close stripes, and thus we propose a compact interferometer design using evanescent coupling. The sensitivity of the design is compared with that achieved using a hand-held sensor based on the Kretschmann style surface plasmon resonance technique. Modeling of the new interferometric sensor is performed for various structural parameters using finite-difference time-domain and COMSOL Multiphysics. The physical mechanisms behind the coupling and propagation of plasmons in this structure are explained in terms of the allowed modes in each section of the device. [ABSTRACT FROM AUTHOR]

In this paper, a plasmonic “ac Wheatstone bridge” circuit is proposed and theoretically modeled for the first time. The bridge circuit consists of three metallic nanoparticles, shaped as rectangular prisms, with two nanoparticles acting as parallel arms of a resonant circuit and the third bridging nanoparticle acting as an optical antenna providing an output signal. Polarized light excites localized surface plasmon resonances in the two arms of the circuit, which generate an optical signal dependent on the phase-sensitive excitations of surface plasmons in the antenna. The circuit is analyzed using a plasmonic coupling theory and numerical simulations. The analyses show that the plasmonic circuit is sensitive to phase shifts between the arms of the bridge and has the potential to detect the presence of single molecules. [ABSTRACT FROM AUTHOR]

This work is devoted to studying unconditionally energy stable and mass-conservative numerical schemes for the following repulsive-productive chemotaxis model: find u ≥ 0, the cell density, and v ≥ 0, the chemical concentration, such that ∂tu - Δu - ∇ ・ (u∇v) = 0 in Ω, t>0, ∂tv - Δv + v = u in Ω, t>0, in a bounded domain Ω ⊆ Rd, d = 2, 3. By using a regularization technique, we propose three fully discrete Finite Element (FE) approximations. The first one is a nonlinear approximation in the variables (u, v); the second one is another nonlinear approximation obtained by introducing σ = ∇v as an auxiliary variable; and the third one is a linear approximation constructed by mixing the regularization procedure with the energy quadratization technique, in which other auxiliary variables are introduced. In addition, we study the well-posedness of the numerical schemes, proving unconditional existence of solution, but conditional uniqueness (for the nonlinear schemes). Finally, we compare the behavior of such schemes throughout several numerical simulations and provide some conclusions. [ABSTRACT FROM AUTHOR]

Copyright of Informacion Tecnica Economica Agraria is the property of Asociacion Interprofesional para el Desarrollo Agrario (AIDA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The potential of using rabbit manure as inoculum for biogas production was evaluated through batch assays using bean straw as substrate. The microbial diversity in the rabbit manure included lignin-degrading bacteria (classes Bacteroidia, Bacilli and Clostridia) as well as key acetoclastic (Matheanosarcina and Methanosaeta), and hydrogenotrophic (Methanobacterium, Methanolinea, and Methanovebribacter) archaea. The effects of particle size, substrate to inoculum ratio (S/X) and pH adjustment were studied to improve the inoculum activity. The adjustment of the pH entailed the highest improvement in methane production (515%) and rate (164%). However, high S/X, (3–4), resulted in the acidification of the processes, denoting an imbalance between hydrolytic bacteria and methanogenic archaea in the rabbit manure. This confirmed that the use of rabbit manure as inoculum could sustain anaerobic digestion from agricultural residues, although a proper enrichment and adaptation is necessary to ensure an appropriate methane production. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos de Investigación Geográfica is the property of Universidad de la Rioja, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We address homogenization problems of variational inequalities for the p-Laplace operator in a domain of R n ( n ≥ 3, p ∈ [ 2 , n) ) periodically perforated by balls of radius O (ε α) where α > 1 and ε is the size of the period. The perforations are distributed along a (n - 1) -dimensional manifold γ , and we impose constraints for solutions and their fluxes (associated with the p-Laplacian) on the boundary of the perforations. These constraints imply that the solution is positive and that the flux is bounded from above by a negative, nonlinear monotonic function of the solution multiplied by a parameter ε - κ , κ ∈ R and ε is a small parameter that we shall make to go to zero. We analyze different relations between the parameters p , n , ε , α and κ , and obtain homogenized problems which are completely new in the literature even for the case p = 2 . [ABSTRACT FROM AUTHOR]

Nothofagus antarctica, is the most important species of the silvopastoral systems of southern Patagonia. However, there is limited information on the ecophysiological response mechanisms of seedlings for survival under different resource availability regimes, and whether such processes may differ between provenances. In this study, we evaluated the functional response to water shortage of seedlings of four N. antarctica provenances grown under controlled conditions. After an initial full irrigation period, seedlings were subjected to a water shortage cycle. Measurements of the diameter at the base of the stem, net photosynthesis (An), stomatal conductance to water vapour (gs), predawn water potential (Ψpd), osmotic potential at maximum and zero turgor (Π100; Π0), relative water content at zero turgor (RWC0) and maximum modulus of elasticity (Emax) were carried out during the experimental period. Differences between provenances concerning An and gs rates were recorded under full irrigation conditions, but were not detected in association with drought stress. All provenances had similar osmotic potential values (Π100 and Π0) at full irrigation, but water shortage led to significant osmotic potential differences between provenances. During the whole experimental period, no significant differences on RWC0 and Emax values were recorded among provenances. Under full irrigation conditions, all N. antarctica provenances had a similar physiological performance which suggests that environmental conditions may be the main driver for phenotypic differences in this species. From the osmotic adjustment results gathered, it is derived that a major osmoregulation capacity in response to water shortage is a common feature of all the N. antarctica provenances evaluated. [ABSTRACT FROM AUTHOR]

Copyright of Acta Ortopédica Mexicana is the property of Sociedad Mexicana de Ortopedia, AC and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cuadernos de Investigación Geográfica is the property of Universidad de la Rioja, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phase transitions in the radical ion salts of Cu(2,5-dimethyl-dicyanoquinonediimine)2 (Cu(DCNQI)2) can be achieved either by ‘‘external’’ pressure or by ‘‘internal’’ pressure. The latter is introduced by chemical modifications at the DCNQI-molecules (e.g., deuteration) or by alloying deuterated Cu(2,5-(CD3)2-DCNQI)2 (d6) with undeuterated Cu(2,5-(CH3)2-DCNQI)2 (h8), giving the mixture (h8/d6) in different ratios. In this work we present simultaneous conductivity (σ) and electron spin resonance (ESR) experiments on differently deuterated Cu(DCNQI)2-systems and on alloys (h8/d6) under external pressure. The anticoincidence of σ and ESR allows the determination of phase transition temperatures even in the absence of electrical contacts. For each system an individual phase diagram is established. Introducing an effective pressure peff=p0+p with p0 being the ‘‘internal’’ (chemical) pressure, a general phase diagram could be constructed by determining the individual p0 value for all systems. For the alloys (h8/d6) the relation ∂p0/∂q=5.0 bar/% (q is the percentage of d6) could be evaluated. The occurrence of a phase transition is associated with a change in the lattice parameters. For that, a structural model of a v-shaped temperature dependence of the unit cell volume V is suggested. For thermodynamic considerations, V is used as order parameter. If this order parameter V crosses critical values Vcbig and Vcsmall from above (cooling) or below (heating), phase transitions from conducting to insulating phases or vice versa are induced. This model explains the phase transition temperatures, the re-entry and the hysteresis effects of all systems qualitatively. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The deuterated dicyanoquinonediimine salt Cu(2-CD3,5-CD3-DCNQI)2, (d6), a highly conductive organic metal, exhibits a phase transition from the metallic to the insulating state at Tc≊60 K. In a wide temperature range we observe an anticoincidence of high conductivity and electron spin resonance (ESR). These experiments were performed simultaneously in our ESR apparatus equipped for application of He pressure up to 200 bar. Near Tc there is a coexistence of conducting (ESR-silent) and insulating (ESR-detectable) domains. This correlation of ESR and conductivity σ points to a percolation limited conductivity. Upper and lower limits of the size of the domains are given. Light shifts Tc to lower temperatures, pressure to higher ones. This could be due to shrinking of the lattice which induces the phase transition when critical structural parameters are approached. This is most probably explained by a simultaneous development of a charge density wave (CDW) and a spin pairing within the DCNQI stack together with the trimerization of the lattice. Systematic measurements by variation of temperature, pressure, and light led to phase diagrams of (d6) and to the understanding of the mechanism of the phase transitions. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]