ALBERT

Beschreibung: Dense SrLa( R 0.5 Ti 0.5 )O 4 ( R= Mg, Zn) ceramics were prepared by a standard solid-state reaction method. The single phase with complex K 2 NiF 4 -type layered perovskite structure and I 4/ mmm space group was revealed by XRD, and the refined structure was analyzed by Rietveld analysis. Significantly improved dielectric constant was obtained in SrLa( R 0.5 Ti 0.5 )O 4 ceramics compared to the analogues SrLaAlO 4 and SrLaGaO 4 , which is attributed to the increasing normalized bond lengths of Sr/La-O(1) and Sr/La-O(2a) bonds and the higher polarizability of ( R 0.5 Ti 0.5 ) 3+ than Al 3+ and Ga 3+ . In addition, τ f converts to a positive value with the increase in dielectric constant. The following microwave dielectric properties were obtained in the dense ceramics: ε r =25.5, Qf= 72 000 GHz, τ f = 29 ppm/°C for SrLa(Mg 0.5 Ti 0.5 )O 4 , and ε r =29.4, Qf= 34 000 GHz, τ f = 38 ppm/°C for SrLa(Zn 0.5 Ti 0.5 )O 4. Furthermore, the stability of K 2 NiF 4 -type structure in MLnB O 4 [ M =Ca, Sr, Ba; Ln =Y, Sm, Nd, La; B= Al, Ga, (Mg 0.5 Ti 0.5 ), (Zn 0.5 Ti 0.5 )] compounds was discussed in relation to the tolerance factor of perovskite layer and the radius ratio of M 2+ and Ln 3+ , based on which near-zero τ f values are expected to be obtained in SrLa( R 0.5 Ti 0.5 )O 4 -SrLaAlO 4 and SrLa( R 0.5 Ti 0.5 )O 4 –SrLaGaO 4 unlimited solid solutions.

Beschreibung: The oxygen nonstoichiometry of SrFeO 3−δ was determined by solid-state Coulometric titration at 750°C-1040°C and 10 −18 ≤ p O 2 (atm)≤0.5. At T ≤850°C, a hysteresis in the oxygen nonstoichiometry (δ) isotherms indicates the presence of a two-phase region corresponding to a mixture of a perovskite and an oxygen vacancy ordered phase. The variation of δ with temperature at fixed p O 2 values and the variation of log( p O 2 ) with reciprocal temperature at fixed δ are reported. The p O 2 at the p - n transition in the electrical conductivity increases as the temperature increases, and the transition in the conductivity isotherm occurs at a composition of SrFeO 2.505(1) at 950°C and SrFeO 2.508(1) at 900°C. Since strontium exclusively occupies the A-site, a simple point defect model that assumes noninteracting defects can describe the isotherms but only at 1040°C; nonideal behavior is observed at lower temperatures. The partial molar thermodynamic quantities for oxygen in SrFeO 3−δ were determined.

Beschreibung: The Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 ceramics for ultra-low temperature co-fired ceramic application were prepared by the solid-state reaction route. The optimized densification temperatures of Ag 2 Mo 2 O 7 and Ag 6 Mo 10 O 33 are 460°C and 500°C, respectively. The phase structures and microstructures of these ceramics were systematically studied. The Ag 2 Mo 2 O 7 ceramic sintered at 460°C/4 h exhibits excellent microwave dielectric properties with ε r =13.3, Q×f =25 300 GHz and τ f =−142 ppm/°C at 9.25 GHz. The Ag 6 Mo 10 O 33 ceramic sintered at 500°C/4 h shows the microwave dielectric properties with ε r =14.0, Q×f =8500 GHz and τ f =−50 ppm/°C at 9.00 GHz. Moreover, when Ag 2 Mo 2 O 7 samples are sintered at ultra-low sintering temperatures of 420°C-490°C, the Q×f values of them are all above 20 000 GHz. Besides, the Ag 2 Mo 2 O 7 ceramic does not react with silver powder or aluminum powder. The variation of relative permittivity, resonant frequency, and Q×f values as a function of operating temperature has been also studied. All the results indicate that the Ag 2 Mo 2 O 7 ceramic is a good candidate for ultra-low temperature co-fired microwave devices.

Beschreibung: Dielectric study over a broadband was carried out from 10 to 70 K on ceramic Gd 1− x Y x MnO 3 ( x =0.2, 0.3 and 0.4). For all the compositions, a prominent sharp peak about ~18 K was observed in the temperature dependence of both ε′( T ) and ε″( T ) at all frequencies, indicating a long-range ferroelectric (FE) transition. Using Cole-Cole fit to the permittivity data, the relaxation time τ and the dielectric strength ∆ε were estimated. Temperature variation of τ( T ) in the Arrhenius representation is found to be nonlinear (non-Debyean relaxation), with increasing barrier-activation energy over successive temperature-windows. Interestingly, for all the compositions, we witness a jump in τ( T ) about the ferroelectric transition temperature, concurred by a broad-maximum in ∆ε( T ),signifying the critical slow down of relaxations near long-range FE-correlations.

Beschreibung: The Cr/Ce-doped YAG transparent ceramic was fabricated by the solid-state reaction in vacuum. The Cr/Ce-doped YAG ceramic phosphor effectively complement the red spectral component and improve the color rendering performance when excited by blue light that is due to the effective energy transfer between Cr 3+ ion and Ce 3+ ion. However, the energy transfer from Ce 3+ to Cr 3+ ion leads to energy loss and therefore the luminous efficacy of the WLED which is composed of blue LED chip and the Cr/Ce-doped YAG ceramic phosphor decreases. The composite phase structure of ceramic phosphor is designed for improving the extraction efficacy and increasing the luminous efficacy by breaking the total internal reflection (TIR) at the interface between air and ceramic.

Beschreibung: The scheme represents the formation of cementitious hydrates from the reaction of anhydrous cement with water and how the kinetics of this reaction can be affected by different types of additives, in particular by comb-copolymers illustrated in the center of this scheme. Such polymers are widely used as dispersants in concrete to enhance its fluidity. More recently, they are playing an increasing role in enabling the production of concrete with a low environmental impact. However, the delay that they almost invariably cause to cement hydration represents a limitation to their use and to the development of alternative binding materials. The paper by Marchon et al. addresses this crucial scientific question and paves the way to the molecular design of optimized chemical admixtures. Cover Illustration by Fabian Rüdy and Stefan auf der Maur, Switzerland. The scheme represents the formation of cementitious hydrates from the reaction of anhydrous cement with water and how the kinetics of this reaction can be affected by different types of additives, in particular by comb-copolymers illustrated in the center of this scheme. Such polymers are widely used as dispersants in concrete to enhance its fluidity. More recently, they are playing an increasing role in enabling the production of concrete with a low environmental impact. However, the delay that they almost invariably cause to cement hydration represents a limitation to their use and to the development of alternative binding materials. The paper by Marchon et al. addresses this crucial scientific question and paves the way to the molecular design of optimized chemical admixtures. Cover Illustration by Fabian Rüdy and Stefan auf der Maur, Switzerland.

Beschreibung: If acquired associations are to accurately represent real relevance relations, there is motivation for the hypothesis that learning will, in some circumstances, be more appropriately modelled, not as direct dependence, but as conditional independence. In a serial compound conditioning experiment, two groups of rats were presented with a conditioned stimulus (CS1) that imperfectly (50%) predicted food, and was itself imperfectly predicted by a CS2. Groups differed in the proportion of CS2 presentations that were ultimately followed by food (25% versus 75%). Thus, the information presented regarding the relevance of CS2 to food was ambiguous between direct dependence and conditional independence (given CS1). If rats learnt that food was conditionally independent of CS2, given CS1, subjects of both groups should thereafter respond similarly to CS2 alone. Contrary to the conditionality hypothesis, subjects attended to the direct food predictability of CS2, suggesting that rats treat even distal stimuli in a CS sequence as immediately relevant to food, not conditional on an intermediate stimulus. These results urge caution in representing indirect associations as conditional associations, accentuate the theoretical weight of the Markov condition in graphical models, and challenge theories to articulate the conditions under which animals are expected to learn conditional associations, if ever.

Beschreibung: Frequently, a set of objects has to be evaluated by a panel of assessors, but not every object is assessed by every assessor. A problem facing such panels is how to take into account different standards among panel members and varying levels of confidence in their scores. Here, a mathematically based algorithm is developed to calibrate the scores of such assessors, addressing both of these issues. The algorithm is based on the connectivity of the graph of assessors and objects evaluated, incorporating declared confidences as weights on its edges. If the graph is sufficiently well connected, relative standards can be inferred by comparing how assessors rate objects they assess in common, weighted by the levels of confidence of each assessment. By removing these biases, ‘true’ values are inferred for all the objects. Reliability estimates for the resulting values are obtained. The algorithm is tested in two case studies: one by computer simulation and another based on realistic evaluation data. The process is compared to the simple averaging procedure in widespread use, and to Fisher's additive incomplete block analysis. It is anticipated that the algorithm will prove useful in a wide variety of situations such as evaluation of the quality of research submitted to national assessment exercises; appraisal of grant proposals submitted to funding panels; ranking of job applicants; and judgement of performances on degree courses wherein candidates can choose from lists of options.

Beschreibung: In this work, an efficient carbothermal reduction–nitridation (CRN) strategy was rationally designed to directly synthesize β-Si 3 N 4 powders with eminent dispersity and granularity uniformity. With the aid of CaO additive, the obtained β-Si 3 N 4 particles were endowed with approximate spherical morphology and smooth surface. The size of β-Si 3 N 4 particles could be regulated in sub-micro and micro scale by altering N 2 pressures. More significantly, the underlying growth mechanism of the β-Si 3 N 4 under elevated N 2 pressure was comprehensively analyzed and tentatively put forward. Benefiting from the remarkable merits, the as-synthesized β-Si 3 N 4 powders showed great potential for alternative fillers in the application of high thermal conductivity plastic packages. This article is protected by copyright. All rights reserved.

Beschreibung: We surveyed 110 country churches in south-western Sweden for presence of brown long-eared bats Plecotus auritus in summer 2016 by visual inspection and/or evening emergence counts. Each church was also classified according to the presence and amount of aesthetic directional lights (flood-lights) aimed on its walls and tower from the outside. Sixty-one of the churches had previously been surveyed by one of us (J.R.) between 1980 and 1990, before lights were installed on Swedish churches, using the same methods. Churches with bat colonies had decreased significantly in frequency from 61% in 1980s to 38% by 2016. All abandoned churches had been fitted with flood-lights in the period between the two surveys. The loss of bat colonies from lit churches was highly significant and most obvious when lights were applied from all directions, leaving no dark corridor for the bats to leave and return to the roost. In contrast, in churches that were not lit, all of 13 bat colonies remained after 25+ years between the surveys. Lighting of churches and other historical buildings is a serious threat to the long-term survival and reproduction of light-averse bats such as Plecotus spp. and other slow-flying species. Bat roosts are strictly protected according to the EU Habitats Directive and the EUROBATS agreement. Lighting of buildings for aesthetic purposes is becoming a serious environmental issue, because important bat roosts are destroyed in large numbers, and the problem should be handled accordingly. As a start, installation of flood-lights on historical buildings should at least require an environmental impact assessment (EIA).

Beschreibung: Unlike mirror self-recognition, recognizing one's own image in delayed video footage may indicate the presence of a concept of self that extends across time and space. While humans typically show this ability around 4 years of age, it is unknown whether this capacity is found in non-human animals. In this study, chimpanzees performed a modified version of the mark test to investigate whether chimpanzees could remove stickers placed on the face and head while watching live and delayed video images. The results showed that three of five chimpanzees consistently removed the mark in delayed-viewing conditions, while they removed the stickers much less frequently in control video conditions which lacked a link to their current state. These findings suggest that chimpanzees, like human children at the age of 4 years and more, can comprehend temporal dissociation in their concept of self.

Beschreibung: We review the literature to identify common problems of decision-making in individuals and groups. We are guided by a Bayesian framework to explain the interplay between past experience and new evidence, and the problem of exploring the space of hypotheses about all the possible states that the world could be in and all the possible actions that one could take. There are strong biases, hidden from awareness, that enter into these psychological processes. While biases increase the efficiency of information processing, they often do not lead to the most appropriate action. We highlight the advantages of group decision-making in overcoming biases and searching the hypothesis space for good models of the world and good solutions to problems. Diversity of group members can facilitate these achievements, but diverse groups also face their own problems. We discuss means of managing these pitfalls and make some recommendations on how to make better group decisions.

Beschreibung: Phase separation and coarsening is a phenomenon commonly seen in binary physical and chemical systems that occur in nature. Often, thermal fluctuations, modelled as stochastic noise, are present in the system and the phase segregation process occurs on a surface. In this work, the segregation process is modelled via the Cahn–Hilliard–Cook model, which is a fourth-order parabolic stochastic system. Coarsening is analysed on two sample surfaces: a unit sphere and a dumbbell. On both surfaces, a statistical analysis of the growth rate is performed, and the influence of noise level and mobility is also investigated. For the spherical interface, it is also shown that a lognormal distribution fits the growth rate well.

Beschreibung: Novel, molecularly imprinted polymers (MIPs) were developed for the highly sensitive and selective recognition of the stress marker cortisol. Oriented, homogeneous cavities with two binding sites for cortisol were fabricated by surface-initiated atom transfer radical polymerization, using a cortisol motif template molecule (TM1) which consists of a polymerizable moiety attached at the 3-carbonyl group of cortisol via an oxime linkage and an adamantane carboxylate moiety coupled with the 21-hydroxyl group. TM1 was orientationally immobilized on a β - cyclodextrin (β-CD)-grafted gold-coated sensor chip by inclusion of the adamantane moiety of TM1, followed by copolymerization of a hydrophilic comonomer, 2-methacryloyloxyethyl phosphorylcholine, with or without a cross-linker, N,N' -methylenebisacrylamide. Subsequent cleavage of the oxime linkage leaves the imprinted cavities that contain dual binding sites—namely, the aminooxy group and β-CD—capable of oxime formation and hydrophobic interaction, respectively. As an application, MIP-based picomolar level detection of cortisol was demonstrated by a competitive binding assay using a fluorescent competitor. Cross-linking of the MIP imparts rigidity to the binding cavities, and improves the selectivity and sensitivity significantly, reducing the limit of detection to 4.8 pM. In addition, detection of cortisol in saliva samples was demonstrated as a feasibility study.

Beschreibung: Iron-based magnetic molecular imprinted polymers (Fe@SiO 2 @MIP) were synthesized for highly selective removal and recognition of di- n -pentyl phthalate (DnPP) from water. Well-defined core-shell Fe@SiO 2 nanoparticles (less than 70 nm) were decorated on MIPs reticular layers to endow DnPP-MIPs with magnetic property for the first time. Five other phthalic acid esters including dimethyl phthalate, diethyl phthalate, dipropyl phthalate, di- n -butyl phthalate and di-iso-octyl phthalate were used to investigate the adsorptive selectivity to DnPP. The designed experiments were carried out to explore the adsorption kinetics, isotherms and thermodynamics and the results demonstrated that the adsorption was a spontaneous, exothermal and physical adsorption process. The materials were proved to be excellent adsorbents in removal of DnPP with an adsorption capacity as high as 194.15 mg g –1 in optimal condition. Furthermore, a magnetic solid phase extraction with Fe@SiO 2 @MIP coupled to high-performance liquid chromatography method was successfully developed for the determination of DnPP, and the proposed method achieved a good linear range of 0.5–250 µg l –1 with a correlation coefficient ( R 2 ) of 0.999 and low limit of detection (LOD) of 0.31 µg l –1 . These materials exhibited excellent capacity in removal and highly sensitive identification of DnPP from aqueous environment samples, and opened a valuable direction for developing new adsorbents for the removal and enrichment of important pollutants.

Beschreibung: Adults are prone to responding erroneously to another's instructions based on what they themselves see and not what the other person sees. Previous studies have indicated that in instruction-following tasks participants make more errors when required to infer another's perspective than when following a rule. These inference-induced errors may occur because the inference process itself is error-prone or because they are a side effect of the inference process. Crucially, if the inference process is error-prone, then higher error rates should be found when the perspective to be inferred is more complex. Here, we found that participants were no more error-prone when they had to judge how an item appeared (Level 2 perspective-taking) than when they had to judge whether an item could or could not be seen (Level 1 perspective-taking). However, participants were more error-prone in the perspective-taking variants of the task than in a version that only required them to follow a rule. These results suggest that having to represent another's perspective induces errors when following their instructions but that error rates are not directly linked to errors in inferring another's perspective.

Beschreibung: The inner ear morphology of 80 snake and lizard species, representative of a range of ecologies, is here analysed and compared to that of the fossil stem snake Dinilysia patagonica , using three-dimensional geometric morphometrics. Inner ear morphology is linked to phylogeny (we find here a strong phylogenetic signal in the data that can complicate ecological correlations), but also correlated with ecology, with Dinilysia resembling certain semi-fossorial forms ( Xenopeltis and Cylindrophis ), consistent with previous reports. We here also find striking resemblances between Dinilysia and some semi-aquatic snakes, such as Myron (Caenophidia, Homalopsidae). Therefore, the inner ear morphology of Dinilysia is consistent with semi-aquatic as well as semi-fossorial habits: the most similar forms are either semi-fossorial burrowers with a strong affinity to water ( Xenopeltis and Cylindrophis ) or amphibious, intertidal forms which shelter in burrows ( Myron). Notably, Dinilysia does not cluster as closely with snakes with exclusively terrestrial or obligate burrowing habits (e.g. scolecophidians and uropeltids). Moreover, despite the above similarities, Dinilysia also occupies a totally unique morphospace, raising issues with linking it with any particular ecological category.

Beschreibung: The intensive use of synthetic pesticides in cowpea storage has led to the development of resistance by Callosobruchus maculatus and subsequent degradation of grain quality. In an attempt to circumvent these constraints, the susceptibility of C. maculatus to 2,2-dichlorovinyldimethyl phosphate (DDVP) and Lippia adoensis essential oil (EO) was investigated and variations in the proportions of nutritional values of treated grains 150 days after storage were assessed. The survival rate was recorded after five generations. The resistance index and biochemical parameters of grains were determined. The results from this study revealed that the survival rate and resistance index significantly increased proportionally with damage in DDVP treatments ( r = 0.889; p = 0.018) while in EO treatments, those values remained low without significant variations ( p = 0.0764) throughout the generations. DDVP stored grains yielded higher crude protein values, but lower carbohydrates, tannins, phenolics and minerals compared to EO. Eighteen amino acids were detected in EO treated grains and 14 in DDVP which was devoid of albumin and prolamin. Lippia adoensis EO could therefore represent a safe alternative bio-pesticide to cope with insect resistance and enhance the nutritional qualities of stored cowpea seeds.

Beschreibung: The development of current surgical treatments for intervertebral disc damage could benefit from virtual environment accounting for population variations. For such models to be reliable, a relevant description of the mechanical properties of the different tissues and their role in the functional mechanics of the disc is of major importance. The aims of this work were first to assess the physiological hoop strain in the annulus fibrosus in fresh conditions ( n = 5) in order to extract a functional behaviour of the extrafibrillar matrix; then to reverse-engineer the annulus fibrosus fibrillar behaviour ( n = 6). This was achieved by performing both direct and global controlled calibration of material parameters, accounting for the whole process of experimental design and in silico model methodology. Direct-controlled models are specimen-specific models representing controlled experimental conditions that can be replicated and directly comparing measurements. Validation was performed on another six specimens and a sensitivity study was performed. Hoop strains were measured as 17 ± 3% after 10 min relaxation and 21 ± 4% after 20–25 min relaxation, with no significant difference between the two measurements. The extrafibrillar matrix functional moduli were measured as 1.5 ± 0.7 MPa. Fibre-related material parameters showed large variability, with a variance above 0.28. Direct-controlled calibration and validation provides confidence that the model development methodology can capture the measurable variation within the population of tested specimens.

Beschreibung: Single-cell responses are shaped by the geometry of signalling kinetic trajectories carved in a multidimensional space spanned by signalling protein abundances. It is, however, challenging to assay a large number (more than 3) of signalling species in live-cell imaging, which makes it difficult to probe single-cell signalling kinetic trajectories in large dimensions. Flow and mass cytometry techniques can measure a large number (4 to more than 40) of signalling species but are unable to track single cells. Thus, cytometry experiments provide detailed time-stamped snapshots of single-cell signalling kinetics. Is it possible to use the time-stamped cytometry data to reconstruct single-cell signalling trajectories? Borrowing concepts of conserved and slow variables from non-equilibrium statistical physics we develop an approach to reconstruct signalling trajectories using snapshot data by creating new variables that remain invariant or vary slowly during the signalling kinetics. We apply this approach to reconstruct trajectories using snapshot data obtained from in silico simulations, live-cell imaging measurements, and, synthetic flow cytometry datasets. The application of invariants and slow variables to reconstruct trajectories provides a radically different way to track objects using snapshot data. The approach is likely to have implications for solving matching problems in a wide range of disciplines.

Beschreibung: The wetting, reactivity and phase formation at the liquid Ni-Al/TiB 2 ceramic interfaces have been investigated at the temperatures close to the Ni-Al liquidus line. The wetting kinetics has been studied by the sessile drop technique utilizing liquid drop dispension and high-speed high-resolution video imaging. It is established that the wetting behavior changes from a non-reactive for the Al-rich melts to a dissolution-reactive for the Ni-rich melts. For the Ni concentration ≥40 at.%, TiB 2 precipitates are found in the solidified Ni-Al droplets after the high-temperature interaction of the melts with TiB 2 substrates. Besides, new (Al,Ti)Ni 3 and (Al,Ti) 2 Ni 21 B 6 phases are formed due to dissolution of TiB 2 ceramic in Ni-rich melts and subsequent solidification. This article is protected by copyright. All rights reserved.

Beschreibung: Searching for layered MAX phase-like materials with properties of both ceramics and metals is a topic in its infancy. Herein, through a combination of crystal structure, electronic structure, chemical bonding and elastic property investigations, we report two MAX phase-like layered materials Rh 2 YSi and Ir 2 YSi. Rh 2 YSi and Ir 2 YSi have bulk modulus B of 150 and 185 GPa, respectively, which are comparable to the typical MAX phases like Ti 2 AlC, Ti 3 AlC 2 and Ti 3 SiC 2 , but much lower shear modulus G (82 and 97 GPa for Rh 2 YSi and Ir 2 YSi, respectively) than MAX phases. The high stiffness is due to the presence of rigid Si2-M-Si3-M (M=Ir, Rh) units, while the low shear deformation resistance is due to the presence of metallic bonds and the weak bonds that link the rigid Si2-M-Si3-M (M=Ir, Rh) units. Based on the low shear deformation resistance and low Pugh's ratio, Rh 2 YSi and Ir 2 YSi are predicted as damage tolerant silicides and promising water vapor resistant interphase materials for SiC f /SiC composites if yttria or yttrium silicates are formed to protect the SiC fibers in oxygen containing environments. The possible slip systems are {0001} 〈2‾1‾10〉 and {11‾20} 〈0001〉 for both Rh 2 YSi and Ir 2 YSi. This article is protected by copyright. All rights reserved.

Beschreibung: As one of common dynamic covalent bonds, acylhydrazone bond plays an important role in developing intelligent responsive materials. In this report, we present acylhydrazone-based dynamic polymers with multi-stimuli responsiveness, particularly metal recognition behaviours and their modulation. A series of polyacylhydrazones with different metal-binding sites were designed and prepared in a modular fashion. Titration of these receptors with a diverse set of metal ions, including Cu 2+ , Zn 2+ and La 3+ , resulted in unique optical changes, and both the sensitivity and selectivity profiles can be regulated. Moreover, the metal-binding feature was facilely modulated by changing the solvent. The addition of weakly basic anions was employed to further fine-tune the responsiveness of the polymers by taking advantage of the cooperative effect with metal coordination. Finally, the sensitive detection of 6-mercaptopurine and pyrophosphate was achieved to demonstrate the application potential of these systems.

Beschreibung: The adhesion strength of a contact between a rotationally symmetric indenter and an elastic half-space is analysed analytically and numerically using an extension of the method of dimensionality reduction for superimposed normal/tangential adhesive contacts. In particular, the dependence of the critical adhesion force on the simultaneously applied tangential force is obtained and the relevant dimensionless parameters of the problem are identified. The fracture criterion used coincides with that suggested by Johnson. In this paper, it is used to develop a method that is applicable straightforwardly to adhesive contacts of arbitrary bodies of revolution with compact contact area.

Beschreibung: The use of information provided by others to tackle life's challenges is widespread, but should not be employed indiscriminately if it is to be adaptive. Evidence is accumulating that animals are indeed selective and adopt ‘social learning strategies’. However, studies have generally focused on fish, bird and primate species. Here we extend research on social learning strategies to a taxonomic group that has been neglected until now: otters (subfamily Lutrinae). We collected social association data on captive groups of two gregarious species: smooth-coated otters ( Lutrogale perspicillata ), known to hunt fish cooperatively in the wild, and Asian short-clawed otters ( Aonyx cinereus ), which feed individually on prey requiring extractive foraging behaviours. We then presented otter groups with a series of novel foraging tasks, and inferred social transmission of task solutions with network-based diffusion analysis. We show that smooth-coated otters can socially learn how to exploit novel food sources and may adopt a ‘copy when young’ strategy. We found no evidence for social learning in the Asian short-clawed otters. Otters are thus a promising model system for comparative research into social learning strategies, while conservation reintroduction programmes may benefit from facilitating the social transmission of survival skills in these vulnerable species.

Beschreibung: Cuvier's beaked whales ( Ziphius cavirostris ) have stranded in association with mid-frequency active sonar (MFAS) use, and though the causative mechanism linking these events remains unclear, it is believed to be behaviourally mediated. To determine whether MFAS use was associated with behavioural changes in this species, satellite tags were used to record the diving and movements of 16 Cuvier's beaked whales for up to 88 days in a region of frequent MFAS training off the coast of Southern California. Tag data were combined with summarized records of concurrent bouts of high-power, surface-ship and mid-power, helicopter-deployed MFAS use, along with other potential covariates, in generalized additive mixed-effects models. Deep dives, shallow dives and surface intervals tended to become longer during MFAS use, with some variation associated with the total amount of overlapping MFAS during the behaviour. These changes in dives and surface intervals contributed to a longer interval between deep dives, a proxy for foraging disruption in this species. Most responses intensified with proximity and were more pronounced during mid-power than high-power MFAS use at comparable distances within approximately 50 km, despite the significantly lower source level of mid-power MFAS. However, distance-mediated responses to high-power MFAS, and increased deep dive intervals during mid-power MFAS, were evident up to approximately 100 km away.

Beschreibung: Restorative brain–computer interfaces (BCIs) have been proposed to enhance stroke rehabilitation. Restorative BCIs are able to close the sensorimotor loop by rewarding motor imagery (MI) with sensory feedback. Despite the promising results from early studies, reaching clinically significant outcomes in a timely fashion is yet to be achieved. This lack of efficacy may be due to suboptimal feedback provision. To the best of our knowledge, the optimal feedback update interval (FUI) during MI remains unexplored. There is evidence that sensory feedback disinhibits the motor cortex. Thus, in this study, we explore how shorter than usual FUIs affect behavioural and neurophysiological measures following BCI training for stroke patients using a single-case proof-of-principle study design. The action research arm test was used as the primary behavioural measure and showed a clinically significant increase (36%) over the course of training. The neurophysiological measures including motor evoked potentials and maximum voluntary contraction showed distinctive changes in early and late phases of BCI training. Thus, this preliminary study may pave the way for running larger studies to further investigate the effect of FUI magnitude on the efficacy of restorative BCIs. It may also elucidate the role of early and late phases of motor learning along the course of BCI training.

Beschreibung: We have characterized the dissolution state of microcrystalline cellulose (MCC) in aqueous tetrabutylammonium hydroxide, TBAH(aq), at different concentrations of TBAH, by means of turbidity and small-angle X-ray scattering. The solubility of cellulose increases with increasing TBAH concentration, which is consistent with solubilization driven by neutralization. When comparing the two polymorphs, the solubility of cellulose I is higher than that of cellulose II. This has the consequence that the dissolution of MCC (cellulose I) may create a supersaturated solution with respect to cellulose II. As for the dissolution state of cellulose, we identify three different regimes. (i) In the stable regime, corresponding to concentrations below the solubility of cellulose II, cellulose is molecularly dissolved and the solutions are thermodynamically stable. (ii) In the metastable regime, corresponding to lower supersaturations with respect to cellulose II, a minor aggregation of cellulose occurs and the solutions are kinetically stable. (iii) In the unstable regime, corresponding to larger supersaturations, there is macroscopic precipitation of cellulose II from solution. Finally, we also discuss strong alkali solvents in general and compare TBAH(aq) with the classical NaOH(aq) solvent.

Beschreibung: We model radicalization in a society consisting of two competing religious, ethnic or political groups. Each of the ‘sects’ is divided into moderate and radical factions, with intra-group transitions occurring either spontaneously or through indoctrination. We also include the possibility of one group violently attacking the other. The intra-group transition rates of one group are modelled to explicitly depend on the actions and characteristics of the other, including violent episodes, effectively coupling the dynamics of the two sects. We use a game theoretic framework and assume that radical factions may tune ‘strategic’ parameters to optimize given utility functions aimed at maximizing their ranks while minimizing the damage inflicted by their rivals. Constraints include limited overall resources that must be optimally allocated between indoctrination and external attacks on the other group. Various scenarios are considered, from symmetric sects whose behaviours mirror each other, to totally asymmetric ones where one sect may have a larger population or a superior resource availability. We discuss under what conditions sects preferentially employ indoctrination or violence, and how allowing sects to readjust their strategies allows for small, violent sects to grow into large, indoctrinated communities.

Beschreibung: Variation in behaviour among group members often impacts collective outcomes. Individuals may vary both in the task that they perform and in the persistence with which they perform each task. Although both the distribution of individuals among tasks and differences among individuals in behavioural persistence can each impact collective behaviour, we do not know if and how they jointly affect collective outcomes. Here, we use a detailed computational model to examine the joint impact of colony-level distribution among tasks and behavioural persistence of individuals, specifically their fidelity to particular resource sites, on the collective trade-off between exploring for new resources and exploiting familiar ones. We developed an agent-based model of foraging honeybees, parametrized by data from five colonies, in which we simulated scouts, who search the environment for new resources, and individuals who are recruited by the scouts to the newly found resources, i.e. recruits. We varied the persistence of returning to a particular food source of both scouts and recruits and found that, for each value of persistence, there is a different optimal ratio of scouts to recruits that maximizes resource collection by the colony. Furthermore, changes to the persistence of scouts induced opposite effects from changes to the persistence of recruits on the collective foraging of the colony. The proportion of scouts that resulted in the most resources collected by the colony decreased as the persistence of recruits increased. However, this optimal proportion of scouts increased as the persistence of scouts increased. Thus, behavioural persistence and task participation can interact to impact a colony's collective behaviour in orthogonal directions. Our work provides new insights and generates new hypotheses into how variations in behaviour at both the individual and colony levels jointly impact the trade-off between exploring for new resources and exploiting familiar ones.

Beschreibung: Fertilization represents a critical stage in biology, where successful alleles of a previous generation are shuffled into new arrangements and subjected to the forces of selection in the next generation. Although much research has been conducted on how variation in morphological and behavioural traits lead to variation in fertilization patterns, surprisingly little is known about fertilization at a molecular level, and specifically about how genes expressed on the sperm and egg themselves influence fertilization patterns. In mammals, several genes have been identified whose products are expressed on either the sperm or the egg, and which influence the fertilization process, but the specific mechanisms are not yet known. Additionally, in 2014 an interacting pair of proteins was identified: ‘Izumo’ on the sperm, and ‘Juno’ on the egg. With the identification of these genes comes the first opportunity to understand the molecular aspects of fertilization in mammals, and to identify how the genetic characteristics of these genes influence fertilization patterns. Here, we review recent progress in our understanding of fertilization and gamete compatibility in mammals, which should provide a helpful guide to researchers interested in untangling the molecular mechanisms of fertilization and the resulting impacts on population biology and evolutionary processes.

Beschreibung: Solitary foraging ants have a navigational toolkit, which includes the use of both terrestrial and celestial visual cues, allowing individuals to successfully pilot between food sources and their nest. One such celestial cue is the polarization pattern in the overhead sky. Here, we explore the use of polarized light during outbound and inbound journeys and with different home vectors in the nocturnal bull ant, Myrmecia midas . We tested foragers on both portions of the foraging trip by rotating the overhead polarization pattern by ±45°. Both outbound and inbound foragers responded to the polarized light change, but the extent to which they responded to the rotation varied. Outbound ants, both close to and further from the nest, compensated for the change in the overhead e-vector by about half of the manipulation, suggesting that outbound ants choose a compromise heading between the celestial and terrestrial compass cues. However, ants returning home compensated for the change in the e-vector by about half of the manipulation when the remaining home vector was short (1–2 m) and by more than half of the manipulation when the remaining vector was long (more than 4 m). We report these findings and discuss why weighting on polarization cues change in different contexts.

Beschreibung: In general, the technologically important ferrites nanoparticles, magnetite and maghemite, are converted from cubic to the more stable rhombohedral structure above 500-700 °C under air/vacuum/inert atmosphere. Here, we report, the superior thermal stability of polymer capped Fe 3 O 4 (PCIO) nanocluster (synthesized using microwave-assisted polyol approach) up to 1000 °C under vacuum and inert atmosphere. Raman spectra of post annealed PCIO nanoclusters show the Fe 3 O 4 phase with carbon signature due to the decomposition of polymer matrix. The carbon layer seems to act as a thermal shield and increases the activation energy thereby preventing the intrusion of heat, oxygen, volatiles mass into the magnetic core. The presence of carbon layer was further confirmed from the high resolution transmission electron microscopic image. After thermal annealing at 1000 °C, PCIO nanoclusters showed superparamagnetic behavior with a saturation magnetization of 89 emu/g, close to the bulk saturation magnetization of Fe 3 O 4 phase. In contrast, the uncoated Fe 3 O 4 (UCIO) nanoclusters decompose at 700 °C into α-Fe 2 O 3 and FeO phases under similar annealing conditions. Our findings open up new possibilities of stabilizing nanomaterials for high temperature applications. This article is protected by copyright. All rights reserved.

Beschreibung: Black glasses are amorphous materials based on silicon oxycarbide. The use of precursors in the form of ladder-like silsesquioxanes enables the control of the amount of carbon ions in the glass network by adjusting ratios of T to D structural units in precursors. In this study, four different sols precursors of four different layers of black glasses on titanium substrates were prepared. The materials were analysed with the use of various spectroscopic and microscopic methods. Formation of continuous and hermetic layers resistant to corrosion was proven. The black glasses layers were examined as materials for biomedical applications. Therefore, preliminary tests of their bioactivity and biocompatibility were performed. The best results were obtained for the material of lower contribution of carbon ions. This article is protected by copyright. All rights reserved.

Beschreibung: Triplex particulate composites composed of boride and carbide ceramics were found to have high strength, hardness, and fracture toughness values. Two compositions consisting of 70:15:15 and 1:1:1 volume ratios of TiB 2, SiC, and B 4 C were produced from commercially available powders by hot-pressing. The 70:15:15 ceramic exhibited a strength of ~1.3 GPa, while the 1:1:1 ceramic had a strength of ~0.9 GPa. These strengths are comparable to super-strong Y 2 O 3 -PSZ and β-SiAlON based composites. The Vickers’ hardness values of these ceramics were ~32 GPa for indent loads of 9.8 N. Hardness increased as indentation load decreased. The 1:1:1 ceramic had a hardness of ~53 GPa at an indentation load of 0.49 N, higher than values reported for so-called “super-hard” ceramics, and comparable to c-BN. This article is protected by copyright. All rights reserved.

Beschreibung: Hafnia (HfO 2 ) and zirconia (ZrO 2 ) are of great interest in the quest for replacing silicon oxide in semiconductor field effect transistors because of their high permittivity. Both exhibit extensive polymorphism and understanding the energetics of their transitions is of major fundamental and practical importance. In the present study, we present a systematic thermodynamic summary of the influence of particle size on thermodynamic phase stability in hafnia and zirconia using recently measured enthalpy data from the literature. The amorphous phase is found to be the most energetically stable above 165 and 363 m 2 /g of surface area for HfO 2 and ZrO 2 , respectively. Below 16 and 20.3 m 2 /g of surface area, respectively, the monoclinic phase is the most energetically stable for HfO 2 and ZrO 2 . At intermediate sizes there are closely balanced energetics among monoclinic, tetragonal, and cubic phases. The energy crossovers reflect decreasing surface enthalpy in the order monoclinic, tetragonal, cubic and amorphous for both hafnia and zirconia. This article is protected by copyright All rights reserved.

Beschreibung: Tridacna derasa shells show a crossed lamellar microstructure consisting of three hierarchical lamellar structural orders. The mineral part is intimately intergrown with 0.9 wt% organics, namely polysaccharides, glycosylated and unglycosylated proteins and lipids, identified by Fourier transform infrared spectrometry. Transmission electron microscopy shows nanometre-sized grains with irregular grain boundaries and abundant voids. Twinning is observed across all spatial scales and results in a spread of the crystal orientation angles. Electron backscatter diffraction analysis shows a strong fibre texture with the [001] axes of aragonite aligned radially to the shell surface. The aragonitic [100] and [010] axes are oriented randomly around [001]. The random orientation of anisotropic crystallographic directions in this plane reduces anisotropy of the Young's modulus and adds to the optimization of mechanical properties of bivalve shells.

Beschreibung: Accurately estimating contacts between animals can be critical in ecological studies such as examining social structure, predator–prey interactions or transmission of information and disease. While biotelemetry has been used successfully for such studies in terrestrial systems, it is still under development in the aquatic environment. Acoustic telemetry represents an attractive tool to investigate spatio-temporal behaviour of marine fish and has recently been suggested for monitoring underwater animal interactions. To evaluate the effectiveness of acoustic telemetry in recording interindividual contacts, we compared co-occurrence matrices deduced from three types of acoustic receivers varying in detection range in a benthic shark species. Our results demonstrate that (i) associations produced by acoustic receivers with a large detection range (i.e. Vemco VR2W) were significantly different from those produced by receivers with smaller ranges (i.e. Sonotronics miniSUR receivers and proximity loggers) and (ii) the position of individuals within their network, or centrality, also differed. These findings suggest that acoustic receivers with a large detection range may not be the best option to represent true social networks in the case of a benthic marine animal. While acoustic receivers are increasingly used by marine ecologists, we recommend users first evaluate the influence of detection range to depict accurate individual interactions before using these receivers for social or predator–prey studies. We also advocate for combining multiple receiver types depending on the ecological question being asked and the development of multi-sensor tags or testing of new automated proximity loggers, such as the Encounternet system, to improve the precision and accuracy of social and predator–prey interaction studies.

Beschreibung: Core–shell structured CaCO 3 microspheres (MSs) were prepared by a facile, one-pot method at room temperature. The adsorbent dosage and adsorption time of the obtained CaCO 3 MSs were investigated. The results suggest that these CaCO 3 MSs can rapidly and efficiently remove 99–100% of anionic dyes within the first 2 min. The obtained CaCO 3 MSs have a high Brunauer–Emmett–Teller surface area (211.77 m 2 g –1 ). In addition, the maximum adsorption capacity of the obtained CaCO 3 MSs towards Congo red was 99.6 mg g –1 . We also found that the core–shell structured CaCO 3 MSs have a high recycling capability for removing dyes from water. Our results demonstrate that the prepared core–shell structured CaCO 3 MSs can be used as an ideal, rapid, efficient and recyclable adsorbent to remove dyes from aqueous solution.

Beschreibung: Atmospheric pressure nonequilibrium plasma jet has been applied to the synthesis of [60]fullerene oxides (C 60 O n ) for the first time. C 60 O and C 60 O 2 were produced and isolated in high yields up to 44% and 21%, respectively. The structural assignment of C 60 O was confirmed by comparison with the reported spectroscopic data. Theoretical calculations of 13 C NMR chemical shifts for eight isomers of C 60 O 2 were performed and compared with the experimental data to assign the most possible structure for the obtained C 60 O 2 dominantly as an e isomer.

Beschreibung: The shapes of vertebrate teeth are often used as hallmarks of diet. Here, however, we demonstrate evidence of frequent piscivory by cartilaginous fishes with pebble-like teeth that are typically associated with durophagy, the eating of hard-shelled prey. High-resolution micro-computed tomography observation of a jaw specimen from one batoid species and visual investigation of those of two additional species reveal large numbers of embedded stingray spines, arguing that stingray predation of a scale rivalling that of the largest carnivorous sharks may not be uncommon for large, predatory batoids with rounded, non-cutting dentition. Our observations demonstrate that tooth morphology is not always a reliable indicator of diet and that stingray spines are not as potent a deterrent to predation as normally believed. In addition, we show that several spines in close contact with the jaw skeleton of a wedgefish ( Rhynchobatus ) have become encased in a disorganized mineralized tissue with a distinctive ultrastructure, the first natural and unequivocal evidence of a callus-building response in the tessellated cartilage unique to elasmobranch skeletons. Our findings reveal sampling and analysis biases in vertebrate ecology, especially with regard to the role of large, predatory species, while also illustrating that large body size may provide an escape from anatomical constraints on diet (e.g. gape size, specialist dentition). Our observations inform our concepts of skeletal biology and evolution in showing that tessellated cartilage—an ancient alternative to bone—is incapable of foreign tissue resorption or of restoring damaged skeletal tissue to its original state, and attest to the value of museum and skeletal specimens as records of important aspects of animal life history.

Beschreibung: Our species is characterized by a great degree of cultural variation, both within and between populations. Understanding how group-level patterns of culture emerge from individual-level behaviour is a long-standing question in the biological and social sciences. We develop a simulation model capturing demographic and cultural dynamics relevant to human cultural evolution, focusing on the interface between population-level patterns and individual-level processes. The model tracks the distribution of variants of cultural traits across individuals in a population over time, conditioned on different pathways for the transmission of information between individuals. From these data, we obtain theoretical expectations for a range of statistics commonly used to capture population-level characteristics (e.g. the degree of cultural diversity). Consistent with previous theoretical work, our results show that the patterns observed at the level of groups are rooted in the interplay between the transmission pathways and the age structure of the population. We also explore whether, and under what conditions, the different pathways can be distinguished based on their group-level signatures, in an effort to establish theoretical limits to inference. Our results show that the temporal dynamic of cultural change over time retains a stronger signature than the cultural composition of the population at a specific point in time. Overall, the results suggest a shift in focus from identifying the one individual-level process that likely produced the observed data to excluding those that likely did not. We conclude by discussing the implications for empirical studies of human cultural evolution.

Beschreibung: The phase structure, dielectric, ferroelectric, and piezoelectric properties of (1-2 x )BiScO 3 - x PbTiO 3 - x PbMg 1/3 Nb 2/3 O 3 ceramics ( x =0.30-0.46) were studied. It was found that an increase in x leads to a structural phase transition between the rhombohedral and tetragonal phase via an intermediate monoclinic phase and to a crossover from the nonergodic relaxor state to the ferroelectric one. It was proposed that at x〉0.42 the phase transition changes from second to first order. The assumption about the existence of a tricritical point on the phase diagram at x ≈0.42 with the enhanced dielectric response has been made. The observed structure-property relationships of the studied solid solutions are discussed. It is shown that the solid solutions with x =0.42 are characterized by the high piezoelectric parameters ( d 33 = 509 pC/N, d 31 = -178 pC/N, d h = 153 pC/N), which makes possible their applications in sonar equipment. This article is protected by copyright. All rights reserved.

Beschreibung: Cr 2 AlC foams have been processed for the first time containing low (35 vol.%), intermediate (53 vol.%) and high (75 vol.%) content of porosity and three ranges of pore size, 90 – 180 μm, 180 – 250 μm and 250 - 400 μm. Sacrificial template technique was used as processing method, utilizing NH 4 HCO 3 as temporary pore former. Cr 2 AlC foams exhibited negligible oxidation up to 800 °C and excellent response up to 1300 °C due to the in-situ formation of an outer thin continuous protective layer of α-Al 2 O 3 . The in-situ α-Al 2 O 3 protective layer covered seamlessly all the external surface of the pores, even when they present sharp angles and tight corners, reducing significantly the further oxidation of the foams. The compressive strength of the foams was 73 and 13 MPa for 53 vol.% and 75 vol.% porosity, respectively, which increased up to 128 and 24 MPa after their oxidation at 1200 °C for 1 hour. The increase in the compressive strength after the oxidation was caused by the switch from inter- to transgranular fracture mode. According to the excellent high temperature response, heat exchangers and catalyst supports are the potential application of these foams. This article is protected by copyright. All rights reserved.

Beschreibung: Single phase, sol–gel prepared Cu 1 –x Fe x O (0 ≤ x ≤ 0.125) powders are characterized in terms of structural, electronic and magnetic properties. Using dielectric and magnetic studies we investigate the coupling of electron and spin. The electrical conductivities and activation energies are studied with increasing Fe content. Modelling of experimental conductivity data emphasizes a single hopping mechanism for all samples except x = 0.125, which have two activation energies. Hole doping is confirmed by confirming a majority Fe 3+ substitution of Cu 2+ in CuO from X-ray photoelectron spectroscopy studies (XPS). Such a substitution results in stabilized ferromagnetism. Fe substitution introduces variation in coercivity as an intrinsic magnetic property in Fe-doped CuO, and not as a secondary impurity phase.

Beschreibung: Vague and/or ad hoc definitions of the area sampled in monitoring efforts are common, and estimates of ecological state variables (e.g. distribution and abundance) can be sensitive to such specifications. The uncertainty in population metrics due to data deficiencies, vague definitions of space and lack of standardized protocols is a major challenge for monitoring, managing and conserving amphibian and reptile populations globally. This is especially true for the slow-worm ( Anguis fragilis ), a cryptic and fossorial legless lizard; uncertainty about spatial variation in density has hindered conservation efforts (e.g. in translocation projects). Spatial capture–recapture (SCR) methods can be used to estimate density while simultaneously and explicitly accounting for space and individual movement. We use SCR to analyse mark–recapture data of the slow-worm that were collected using artificial cover objects (ACO). Detectability varied among ACO grids and through the season. Estimates of slow-worm density varied across ACO grids (13, 45 and 46 individuals ha –1 , respectively). The estimated 95% home range size of slow-worms was 0.38 ha. Our estimates provide valuable information about slow-worm spatial ecology that can be used to inform future conservation management.

Beschreibung: Animal reproductive cycles are commonly triggered by environmental cues of favourable breeding conditions. In arid environments, rainfall may be the most conspicuous cue, but the effects on reproduction of the high inter- and intra-annual variation in temperature remain poorly understood, despite being relevant to the current context of global warming. Here, we conducted a multiyear examination of the relationships between a suite of measures of temperature and rainfall, and the onset and length of the breeding season, the probability of breeding and reproductive output in an arid-region passerine, the sociable weaver ( Philetairus socius ). As expected, reproductive output increased with rainfall, yet specific relationships were conditional on the timing of rainfall: clutch production was correlated with rainfall throughout the season, whereas fledgling production was correlated with early summer rainfall. Moreover, we reveal novel correlations between aspects of breeding and temperature, indicative of earlier laying dates after warmer springs, and longer breeding seasons during cooler summers. These results have implications for understanding population trends under current climate change scenarios and call for more studies on the role of temperature in reproduction beyond those conducted on temperate-region species.

Beschreibung: In this work, we explore epidemiological dynamics by the example of tuberculosis in Russian Federation. It has been shown that the epidemiological dynamics correlates linearly with the virulence of Mycobacterium tuberculosis during the period 1987–2012. To construct an appropriate model, we have analysed (using LogLet decomposition method) epidemiological World Health Organization (WHO) data (period 1980–2014) and obtained, as result of their integration, a curve approximated by a bi-logistic function. This fact allows a subdivision of the whole population into parts, each of them satisfies the Verhulst-like models with different constant virulences introduced into each subsystem separately. Such a subdivision could be interconnected with the heterogeneous structure of mycobacterial population that has a high ability of adaptation to the host and strong mutability.

Beschreibung: In three experiments, we asked whether diverse scripts contain interpretable information about the speech sounds they represent. When presented with a pair of unfamiliar letters, adult readers correctly guess which is /i/ (the ‘ee’ sound in ‘feet’), and which is /u/ (the ‘oo’ sound in ‘shoe’) at rates higher than expected by chance, as shown in a large sample of Singaporean university students (Experiment 1) and replicated in a larger sample of international Internet users (Experiment 2). To uncover what properties of the letters contribute to different scripts' ‘guessability,’ we analysed the visual spatial frequencies in each letter (Experiment 3). We predicted that the lower spectral frequencies in the formants of the vowel /u/ would pattern with lower spatial frequencies in the corresponding letters. Instead, we found that across all spatial frequencies, the letter with more black/white cycles (i.e. more ink) was more likely to be guessed as /u/, and the larger the difference between the glyphs in a pair, the higher the script's guessability. We propose that diverse groups of humans across historical time and geographical space tend to employ similar iconic strategies for representing speech in visual form, and provide norms for letter pairs from 56 diverse scripts.

Beschreibung: A new approach to modelling pedestrians' avoidance dynamics based on a Fokker–Planck (FP) Nash game framework is presented. In this framework, two interacting pedestrians are considered, whose motion variability is modelled through the corresponding probability density functions (PDFs) governed by FP equations. Based on these equations, a Nash differential game is formulated where the game strategies represent controls aiming at avoidance by minimizing appropriate collision cost functionals. The existence of Nash equilibria solutions is proved and characterized as a solution to an optimal control problem that is solved numerically. Results of numerical experiments are presented that successfully compare the computed Nash equilibria to the output of real experiments (conducted with humans) for four test cases.

Beschreibung: Similar to other leaf beetles, rosemary beetles Chrysolina americana exhibit a distinct sexual dimorphism in tarsal attachment setae. Setal discoid terminals occur only in males, and they have been previously associated with a long-term attachment to the female's back (elytra) during copulation and mate guarding. For the first time, we studied living males and females holding to female's elytra. Pull-off force measurements with a custom-made tribometer featuring a self-aligning sample holder confirmed stronger attachment to female elytra compared with glass in both males and females; corresponding to 45 and 30 times the body weight, respectively. In line with previous studies, males generated significantly higher forces than females on convex elytra and flat glass, 1.2 times and 6.8 times, respectively. Convex substrates like elytra seem to improve the attachment ability of rosemary beetles, because they can hold more strongly due to favourable shear angles of legs, tarsi and adhesive setae. A self-aligning sample holder is found to be suitable for running force measurement tests with living biological samples.

Beschreibung: Suprathreshold stochastic resonance (SSR) is a distinct form of stochastic resonance, which occurs in multilevel parallel threshold arrays with no requirements on signal strength. In the generic SSR model, an optimal weighted decoding scheme shows its superiority in minimizing the mean square error (MSE). In this study, we extend the proposed optimal weighted decoding scheme to more general input characteristics by combining a Kalman filter and a least mean square (LMS) recursive algorithm, wherein the weighted coefficients can be adaptively adjusted so as to minimize the MSE without complete knowledge of input statistics. We demonstrate that the optimal weighted decoding scheme based on the Kalman–LMS recursive algorithm is able to robustly decode the outputs from the system in which SSR is observed, even for complex situations where the signal and noise vary over time.

Beschreibung: Predators often display dietary shifts in response to fluctuating prey in cyclic systems, but little is known about predator diets in systems that experience non-cyclic prey irruptions. We tracked dietary shifts by feral cats ( Felis catus ), red foxes ( Vulpes vulpes ) and dingoes ( Canis dingo ) through a non-cyclic irruption of small mammalian prey in the Simpson Desert, central Australia. We predicted that all three predators would alter their diets to varying degrees as small mammals declined post irruption, and to test our predictions we live-trapped small mammals through the irruption event and collected scats to track predator diets. Red foxes and dingoes included a broader variety of prey in their diets as small mammals declined. Feral cats did not exhibit a similar dietary shift, but did show variable use and selectivity of small mammal species through the irruption cycle. Results were largely consistent with prior studies that highlighted the opportunistic feeding habits of the red fox and dingo. They also, however, showed that feral cats may exhibit less dietary flexibility in response to small mammal irruptions, emphasizing the importance of tracking predator diets before, during and after irruption events.

Beschreibung: Trace elements such as zinc and iron are essential for the proper function of biochemical processes, and their uptake and bioavailability are dependent on their chemical form. Supplementation of trace metals through nanostructured materials is a new field, but its application raises concerns regarding their toxicity. Here, we compared the intracellular zinc uptake of different sources of zinc: zinc sulfate, and ZnO and core-shell α-Fe 2 O 3 @ZnO nanoparticles, coated or uncoated with inulin, an edible and biocompatible polysaccharide. Using mussel haemocytes, a well-known model system to assess nanomaterial toxicity, we simultaneously assessed zinc accumulation and multiple cellular response endpoints. We found that intracellular zinc uptake was strongly enhanced by inulin coating, in comparison to the uncoated nanoparticles, while no significant effects on cell death, cell viability, mitochondrial membrane integrity, production of reactive oxygen species or lysosome abundance were observed at concentrations up to 20 ppm. Since no significant increments in toxicity were observed, the coated nanomaterials may be useful to increase in vivo zinc uptake for nutritional applications.

Beschreibung: In this work, a small amount of CaO single dopant was adopted to realize the densification and microstructure control of fine grained YAG ceramic with excellent optical quality, by a simple solid state reaction and one-step vacuum sintering method. Then, highly transparent YAG ceramics (T=84.4% at 1064 nm) were obtained just after vacuum sintering at 1820 °C for 8h. The average grain size was only 2.7 μm, when the total amount of CaO was as low as 0.045 wt.%. The effect of CaO on the microstructural evolution and optical property of the as-fabricated YAG ceramics was systematically investigated in detail. It was found that CaO dopant promoted both densification and grain growth of YAG ceramics when the sintering temperature was lower than 1660 °C, however it dramatically inhibited grain growth when the sintering temperature was further increased. This article is protected by copyright. All rights reserved.

Beschreibung: Si 3 N 4 @(TiN-Si 3 N 4 ) composites with hetero-shelled structure were designed for enhanced conductivity and successfully synthesized through the simultaneous reduction and in-situ co-coating process in liquid ammonia at around -40 °C. The hetero-shells were composed of nano-sized TiN and Si 3 N 4 particles which were amorphous with the size ranging from 10 nm to 40 nm. Using spark plasma sintering (SPS) dense bulk composite with 〉98.1% relative density of theoretical value were obtained and their electrical conductivity were increased to an adequate value (6.62×10 2 S·cm −1 ) for electrical discharge machining (EDM) by compositing 15 vol % TiN to Si 3 N 4 , which is superior to the previous reports. The excellent electric performance could be attributed to the hetero-shelled structure which guarantees the conductive network can be formed and kept with minimal TiN content. The nano-sized Si 3 N 4 powders in the shells reduce the content of conductive powders and limit the growth of TiN particles. This article is protected by copyright. All rights reserved.

Beschreibung: Porcelain stoneware was consolidated by flash sintering under DC polarization using current densities in the range 4 – 20 mA/mm 2 . The results show the applicability of this innovative sintering technology to a material whose densification occurs by vitrification, thus allowing to extend the possible application field of flash sintering to traditional ceramics. Using appropriate current density, the flash sintered samples are dense, homogeneous and well-vitrified. XRD and microstructural analysis points out the formation of primary mullite while secondary mullite is only sporadically observed. In addition, comparison between flash sintering and fast firing shows that the densification obtained in the selected ceramic system via the former route can not be reproduced just by a rapid heating process. This article is protected by copyright. All rights reserved.

Beschreibung: It has been claimed that disappearance of the {110} reflection in powder x-ray diffraction of MXene is indicative of shearing or general disorder of restacking of MXene flakes, such as in films. We correct this oversight here and provide experimental justification. Further, our methods provide a simple way to estimate a unit cell parameters when the relevant reflections are not present in most reports of MXene films. This article is protected by copyright. All rights reserved.

Beschreibung: Hi-Nicalon-S/α-Y 2 Si 2 O 7 /SiC minicomposites were formed by polymer infiltration pyrolysis (PIP) and characterized by TEM, SEM fractography, tensile testing, and fiber push-in testing. All minicomposites with α-Y 2 Si 2 O 7 fiber coatings had strengths significantly higher than the control samples without fiber coatings. Extensive fiber pullout with debonding at the coating-fiber interface or within the coating itself was observed in minicomposites with Y 2 Si 2 O 7 fiber coatings, but no debonding was observed in minicomposites without fiber coatings. Debond energies of 4.5±3, 4.6 ±3 J/m 2 and average sliding stresses of 91±40, 94±40 MPa were measured by fiber push-in tests. This article is protected by copyright. All rights reserved.

Beschreibung: A comparative study of reactive melt infiltration using Si and Si-Y alloys is presented to provide insight into the governing processes that control the effectiveness of the melt interaction with a carbonaceous preform and the temperature capability of the SiC matrix for ceramic matrix composites. Through experiments on two substantially different scales of capillaries in porous graphite tubes using Si and Si-Y alloys, the current study has characterized the phenomena that play a role in the infiltration of the melt and its reaction with the preform. It is shown that (i) the interface reaction controls wetting in both large and small capillaries and the climb rate is enhanced by the presence of Y; (ii) reaction choking occurs at critical throats within the pore network, usually behind the infiltration front; and (iii) different residual silicides can form during reaction and upon cooling. A potential mechanism for SiC growth is described, and the implications for the interplay between SiC growth and infiltration are discussed. This article is protected by copyright. All rights reserved.

Beschreibung: We present an algorithm based on maximum-likelihood analysis for the automated recognition of objects, and estimation of their pose, from 3D point clouds. Surfaces segmented from depth images are used as the features, unlike ‘interest point’-based algorithms which normally discard such data. Compared to the 6D Hough transform, it has negligible memory requirements, and is computationally efficient compared to iterative closest point algorithms. The same method is applicable to both the initial recognition/pose estimation problem as well as subsequent pose refinement through appropriate choice of the dispersion of the probability density functions. This single unified approach therefore avoids the usual requirement for different algorithms for these two tasks. In addition to the theoretical description, a simple 2 degrees of freedom (d.f.) example is given, followed by a full 6 d.f. analysis of 3D point cloud data from a cluttered scene acquired by a projected fringe-based scanner, which demonstrated an RMS alignment error as low as 0.3 mm.

Beschreibung: The pressures of selection acting on transmission of information by acoustic signals are particularly high in long-distance communication networks. Males of the North African houbara bustard ( Chlamydotis undulata undulata ) produce extremely low-frequency vocalizations called ‘booms’ as a component of their courtship displays. These displays are performed on sites separated by a distance of on average 550 m, constituting exploded leks. Here, we investigate the acoustic features of booms involved in species-specific identity. We first assessed the modifications of acoustic parameters during boom transmission at long range within the natural habitat of the species, finding that the frequency content of booms was reliably transmitted up to 600 m. Additionally, by testing males' behavioural responses to playbacks of modified signals, we found that the presence of the second harmonic and the frequency modulation are the key parameters for species identification, and also that a sequence of booms elicited stronger responses than a single boom. Thus, the coding–decoding process relies on redundant and propagation-resistant features, making the booms particularly well adapted for the long-range transmission of information between males. Moreover, by experimentally disentangling the presentation of visual and acoustic signals, we showed that during the booming phase of courtship, the two sensory modalities act in synergy. The acoustic component is dominant in the context of intra-sexual competition. While the visual component is not necessary to induce agonistic response, it acts as an amplifier and reduces the time of detection of the signaller. The utilization of these adaptive strategies allows houbara males to maximize the active space of vocalizations emitted in exploded leks.

Beschreibung: A generalized solution procedure is developed for in-plane free vibration of rectangular and annular sectorial plates with general boundary conditions. For the annular sectorial plate, the introduction of a logarithmic radial variable simplifies the basic theory and the expression of the total energy. The coordinates, geometric parameters and potential energy for the two different shapes are organized in a unified framework such that a generalized solving procedure becomes feasible. By using the improved Fourier–Ritz approach, the admissible functions are formulated in trigonometric form, which allows the explicit assembly of global mass and stiffness matrices for both rectangular and annular sectorial plates, thereby making the method computationally effective, especially when analysing annular sectorial plates. Moreover, the improved Fourier expansion eliminates the potential discontinuity of the original normal and tangential displacement functions and their derivatives in the entire domain, and accelerates the convergence. The generalized Fourier–Ritz approach for both shapes has the characteristics of generality, accuracy and efficiency. These features are demonstrated via a few numerical examples.

Beschreibung: Impaired response inhibition is an important factor in tobacco dependence. We examined the effects of inhibitory control training (ICT) on inhibition, smoking resistance and cigarette use. Smokers ( n = 55) abstained from smoking for 12 h prior to testing. On the test day, participants recorded cigarette use and completed pre-training measures of global and cue-specific (smoking-related) response inhibition. Participants were randomized to either an active or a control ICT group. The active group was required to repeatedly inhibit a response towards smoking cues (100%), while the control group was required to inhibit a response towards smoking and neutral cues with equal frequency (50%). Participants performed post-training measures of response inhibition, smoking resistance and cigarette use. Inhibition data did not indicate time (pre-training, post-training) x group (active training, control training) or time x group x cue (smoking, neutral) interactions. There was weak evidence that smokers in the active group were more likely to resist smoking than those in the control group. Cigarette use data did not indicate a time x group interaction. Our data suggest that ICT may enhance the ability to resist smoking, indicating that training may be a promising adjunct to smoking pharmacotherapy.

Beschreibung: We investigated the effects of word order and prosody on word learning in school-age children. Third graders viewed photographs belonging to one of three semantic categories while hearing four-word nonsense utterances containing a target word. In the control condition, all words had the same pitch and, across trials, the position of the target word was varied systematically within each utterance. The only cue to word–meaning mapping was the co-occurrence of target words and referents. This cue was present in all conditions. In the Utterance-final condition, the target word always occurred in utterance-final position, and at the same fundamental frequency as all the other words of the utterance. In the Pitch peak condition, the position of the target word was varied systematically within each utterance across trials, and produced with pitch contrasts typical of infant-directed speech (IDS). In the Pitch peak + Utterance-final condition, the target word always occurred in utterance-final position, and was marked with a pitch contrast typical of IDS. Word learning occurred in all conditions except the control condition. Moreover, learning performance was significantly higher than that observed with simple co-occurrence ( control condition) only for the Pitch peak + Utterance-final condition. We conclude that, for school-age children, the combination of words' utterance-final alignment and pitch enhancement boosts word learning.

Beschreibung: West Nile virus (WNV) is the most widely distributed arbovirus in the world and the spread is influenced by complex factors including weather conditions and urban environmental settings like storm water management ponds (SWMP). The purpose of this work was to develop an ordinary differential equation model to explore the impacts of SWMP, temperature and precipitation on WNV vector abundance and the transmission of WNV between mosquito and bird populations. The model was used to analyse how weather conditions and SWMP can influence the basic reproduction number. The results found that an excess of precipitation and fiercer intraspecific competition will reduce vector population and the peak value of infectious vectors and birds. This information can be used to identify measures that would be useful to control larval abundance in SWMP and the transmission of WNV.

Beschreibung: Precision and reliability of barcode-based biodiversity assessment can be affected at several steps during acquisition and analysis of data. Identification of operational taxonomic units (OTUs) is one of the crucial steps in the process and can be accomplished using several different approaches, namely, alignment-based, probabilistic, tree-based and phylogeny-based. The number of identified sequences in the reference databases affects the precision of identification. This paper compares the identification of marine nematode OTUs using alignment-based, tree-based and phylogeny-based approaches. Because the nematode reference dataset is limited in its taxonomic scope, OTUs can only be assigned to higher taxonomic categories, families. The phylogeny-based approach using the evolutionary placement algorithm provided the largest number of positively assigned OTUs and was least affected by erroneous sequences and limitations of reference data, compared to alignment-based and tree-based approaches.

Beschreibung: 〈001〉-textured 0.99(K 0.49 Na 0.49 Li 0.02 )(Nb 0.97- x Sb 0.03 Ta x )O 3 -0.01CaZrO 3 [abbreviated as 0.99KNLN 0.97- x ST x -0.01CZ, x = 0.03, 0.07, 0.10, 0.15, 0.20, 0.25] ceramics were prepared by templated grain growth (TGG) method and a two-step sintering process. Giant longitudinal piezoelectric coefficient d 33 (391 pC/N) and piezoelectric strain coefficient d 33 * (630 pm/V under an AC E-field of 20 kV/cm) can be obtained in the textured ceramics with x = 0.25. All textured ceramics display superior k p (〉 54%) and g 33 (〉 23 × 10 -3 Vm/N) which are in an order of magnitude with PZT ceramics. The maximum value of k p (~ 63.3%) obtained in textured ceramics with x = 0.15 is higher than that of famous textured LF4 ceramics. Excellent comprehensive properties suggest that 〈001〉-textured 0.99KNLN 0.97- x ST x -0.01CZ ceramics are promising candidates in the field of lead-free piezoelectric materials. This article is protected by copyright. All rights reserved.

Beschreibung: Herein, enhancement of dye-sensitized solar cell (DSC) performance is reported by combining the merits of the dye loading of TiO 2 nanoparticles and light scattering, straight carrier transport path and efficient electron collection efficiency of TiO 2 cubes. We fabricate DSC devices with various arrangement styles and compositions of the electrodes in the forms of monolayer and double layer films. For this purpose, the solvothermal synthesized TiO 2 cubic particles (100-600 nm) are employed as the scattering layer, whereas TiO 2 nanoparticles (15-30 nm) synthesized via a combination of solvothermal and sol-gel routes are used as the active layer of devices. We improve the photovoltaic characteristics of DSCs by two mechanisms. First, the light harvesting of DSC devices made of nanoparticles is improved by controlling the thickness of monolayer films, reaching the highest efficiency of 7.0%. Second, the light scattering and electron collection efficiency are enhanced by controlling the composition of double layer films composed of mixtures of TiO 2 nanoparticles and cubes, obtaining the maximum efficiency of 8.21%. The enhancements are attributed to balance between charge transfer resistance and charge recombination of photo-generated electrons as well as dye loading and light scattering. This article is protected by copyright. All rights reserved.

Beschreibung: Despite enormous interest in calcium silicate hydrate (C-S-H), its detailed atomic structure and intrinsic deformation under an external load are lacking. This study demonstrates the nanostructural deformation process of C-S-H in tricalcium silicate (C 3 S) paste as a function of applied stress by interpreting atomic pair distribution function (PDF) based on in situ X-ray scattering. Three different strains in C 3 S paste under compression were compared using a strain gauge, Bragg peak shift, and the real space PDF. PDF refinement revealed that the C-S-H phase mostly contributed to PDF from 0 to 20 Å whereas crystalline phases dominated that beyond 20 Å. The short-range atomic strains exhibited two regions for C-S-H: I) plastic deformation (0–10 MPa) and II) linear elastic deformation (〉10 MPa), whereas the long-range deformation beyond 20 Å was similar to that of Ca(OH) 2 . Below 10 MPa, the short-range strain was caused by the densification of C-S-H induced by the removal of interlayer or gel-pore water. The strains is likely to be recovered when the removed water returns to C-S-H. This article is protected by copyright. All rights reserved.

Beschreibung: Nanoparticles of Bi 2 Ti 2 O 7 pyrochlore were synthesized by a coprecipitation method. They exhibit a high visible-light photoactivity for decolourization of a methyl-orange dye solution in presence of a sacrificial agent, H 2 O 2 . The same pyrochlore system with a Ag co-catalyst showed even faster kinetics under only visible light and an unprecedentedly high photoactivity in the UV range. This article is protected by copyright. All rights reserved.

Beschreibung: The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles ( Eretmochelys imbricata ) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

Beschreibung: Stellar evolution computations provide the foundation of several methods applied to study the evolutionary properties of stars and stellar populations, both Galactic and extragalactic. The accuracy of the results obtained with these techniques is linked to the accuracy of the stellar models, and in this context the correct treatment of the transport of chemical elements is crucial. Unfortunately, in many respects calculations of the evolution of the chemical abundance profiles in stars are still affected by sometimes sizable uncertainties. Here, we review the various mechanisms of element transport included in the current generation of stellar evolution calculations, how they are implemented, the free parameters and uncertainties involved, the impact on the models and the observational constraints.

Beschreibung: Ethiopia is a world biodiversity hotspot and harbours levels of biotic endemism unmatched in the Horn of Africa, largely due to topographic—and thus habitat—complexity, which results from a very active geological and climatic history. Among Ethiopian vertebrate fauna, amphibians harbour the highest levels of endemism, making amphibians a compelling system for the exploration of the impacts of Ethiopia's complex abiotic history on biotic diversification. Grass frogs of the genus Ptychadena are notably diverse in Ethiopia, where they have undergone an evolutionary radiation. We used molecular data and expanded taxon sampling to test for cryptic diversity and to explore diversification patterns in both the highland radiation and two widespread lowland Ptychadena . Species delimitation results support the presence of nine highland species and four lowland species in our dataset, and divergence dating suggests that both geologic events and climatic fluctuations played a complex and confounded role in the diversification of Ptychadena in Ethiopia. We rectify the taxonomy of the endemic P. neumanni species complex, elevating one formally synonymized name and describing three novel taxa. Finally, we describe two novel lowland Ptychadena species that occur in Ethiopia and may be more broadly distributed.

Beschreibung: A model for the fracture strength of brittle materials controlled by blunt (spherical) scratches is developed and compared with measurements on a polycrystalline alumina. The model is based on a residual stress-intensity factor for median cracks at scratches that include a localized plastic deformation zone formed by dragged spherical contacts. The stress-intensity factor depends non-linearly on the normal contact load P , resulting in a predicted strength variation of P −3/4 . The strength result validates previous claims and extends the overall indentation-strength framework. However, the result has only limited effectiveness in describing experimental measurements, pertaining only to ideal blunt scratches formed over a limited load domain. This article is protected by copyright. All rights reserved.

Beschreibung: The first systematic study of the BaO–B 2 O 3 system and barium orthoborate Ba 3 B 2 O 6 (3BaO·B 2 O 3 ) was reported in 1949. Thereafter, the system was repeatedly refined but the structure of Ba 3 B 2 O 6 compound has not been adequately studied yet. In our study we have, for the first time, obtained the crystalline samples of Ba 3 B 2 O 6 . The solved structure ( Pbam , a = 13.5923(4) Å, b = 13.6702(4) Å, c = 14.8894(3) Å) belongs to the class of ‘anti-zeolite’ borates with a pseudotetragonal [ Ba 12 (BO 3 ) 6 ] 6+ cation pattern which contains channels along the c axis filled with anionic clusters. The Ba 3 B 2 O 6 compound may be regarded as a fluorine-free end-member of the Ba 3 (BO 3 ) 2– x F 3 x solid solution. The BaO–B 2 O 3 phase diagram presented in our study is based on our research and literature data. This article is protected by copyright. All rights reserved.

Beschreibung: Hi-Nicalon TM -S SiC fiber was heat-treated for one hour at 1300, 1400, and 1500°C in argon with pO 2 of 3.7, 10, 20, 50, 100, and 200 ppm. Fiber strengths were measured by 30 single-filament tensile tests. Fiber microstructure and surface morphology were characterized by TEM. Active oxidation occurred in all cases except at 1500°C with 200 ppm pO 2 , 1400°C with 100 ppm pO 2 or higher, and 1300°C with 50 ppm pO 2 or higher. When active oxidation did not occur, a glass SiO 2 scale formed at 1300 and 1400°C, and a cristobalite scale formed at 1500°C. The thickness of these scales was much larger than that predicted by linear dependence of oxidation rate on pO 2 . Fiber strengths were lowest after heat-treatment at 1300°C and a pO 2 of 3.7 ppm, 1400°C and a pO 2 of 20 ppm, and 1500°C and a pO 2 of 200 ppm. Active oxidation caused fiber surface roughening, but no obvious changes to the internal fiber microstructure. Decreased fiber strength correlated with increased fiber surface roughness, but roughness magnitudes were not large enough to explain the amount by which strength was degraded. Fiber strengths, surface roughness, scale thicknesses, and the passive-active oxidation transition for SiC are compared with previous observations. Possible strength degradation mechanisms are discussed. This article is protected by copyright. All rights reserved.

Beschreibung: The interaction of fully dense 45S5-bioglass derived samples produced by Spark Plasma Sintering (SPS) with Simulated Body Fluid (SBF) solution was investigated in detail taking advantage of the Rietveld refinement method to quantitatively evidence the corresponding microstructural and compositional changes. It is observed that, when the original amorphous nature is mostly (75 wt.%) preserved in the material during sintering (550 °C, 2 min), the resulting specimens dissolve faster and determine relatively higher pH increase and ions release in the SBF solution. Correspondingly, a relatively lower amount of hydroxycarbonate apatite (HCA) is formed on their surface. In contrast, a more extensive apatite layer with trabecular structure is generated within 3 days storage on the surface of fully crystallized samples obtained at 600 °C by SPS, which only consists of Na-Ca silicate grains (20 nm). Moreover, as the sintering temperature and dwell time were increased to 700 °C and 20 min, respectively, a rhenanite-like phase was also formed (about 15 wt.%), other than crystallites growth to 90 nm. Interestingly, the presence of rhenanite provides a beneficial contribution for the production of the HCA layer, which was found the largest for this system when considering storage periods of 7 and 14 days, respectively. This article is protected by copyright All rights reserved.

Beschreibung: Niobium alkali germanate glasses were synthesized by the melt-quenching technique. The ternary system (90-x)GeO 2 -xNb 2 O 5 -10K 2 O forms homogeneous glasses with x ranging from 0 to 20mol%. Samples were investigated by DSC and XRD analysis, FTIR and Raman spectroscopy, and optical absorption. Structural and physical features are discussed in terms of Nb 2 O 5 content. The niobium content increase in the glass network strongly modifies the thermal, structural and optical properties of alkali germanate glasses. DSC, Raman and FTIR analysis suggest niobium addition promotes NbO 6 groups insertion close to GeO 4 units of the glass network. XRD analysis also pointed out that samples containing high niobium oxide contents exhibit preferential niobium oxide rich phase after crystallization after heat treatment, which is similar to orthorhombic Nb 2 O 5 . Absorption spectra revealed high transmission range between 400nm to 6.2μm, added to a considerably decreased hydroxyl group content as the addition of niobium in the alkali germanate network. The niobium oxide rich phase crystallization process was studied and activation energy was determined, as well as nucleation and crystal growth temperatures and time for obtaining transparent glass-ceramics. This article is protected by copyright. All rights reserved.

Beschreibung: The effects of fluorine and nitrogen substitution for oxygen in aluminosilicate glasses, effectively oxyfluoronitride (OFN) glasses, modified by calcium, calcium – yttrium or calcium – magnesium on thermal and physical / mechanical properties have been compared. Thus, forty-two glasses in the Ca–(Mg)–(Y)–Si–Al–O–(N)–(F) system have been prepared and characterized with respect to density (ρ), molar volume (MV), compactness (C), free volume (FV), glass transition temperatures measured by DTA (T g, DTA ) and dilatometry (T g,dil ), dilatometric softening point (T DS ), microhardness (μHv) and Young's modulus (E). Gradients of property variation with nitrogen or fluorine substitutions for oxygen are similar for all three different oxyfluoronitride glass systems and are comparable with those reported for other OFN glasses, again indicating independent and additive effects of nitrogen and fluorine. In attempting to further understand how fluorine affects the cross-link density (CLD) in OFN glasses, it becomes apparent that it is necessary to allow for a greater contribution by aluminium in a modifier role as fluorine content is increased. This modified calculation of CLD values results in good linear fits between T g and CLD values. This analysis clearly demonstrates and endorses the concepts that thermal properties are related to CLD whilst physical / mechanical properties are dependent on glass compactness. This article is protected by copyright. All rights reserved.

Beschreibung: In this paper we report for the first time synthesis of Eu 3+ doped transparent glass-ceramics (TGC) with BaBi 2 Ta 2 O 9 (BBT) as the major crystal phase using the glass system SiO 2 -K 2 O-BaO-Bi 2 O 3 -Ta 2 O 5 by melt quenching technique followed by controlled crystallization through ceramming heat-treatment. DSC studies were conducted in order to determine a novel heat-treatment protocol to attain transparent GCs by controlling crystal growth. The structural properties of the BBT GCs have been investigated using XRD, FE-SEM, TEM and FTIR reflectance spectroscopy. Optical band gap energies of the glass-ceramic samples were found to decrease with respect to the precursor glass. An increased intensity of emission along with increase in the average lifetime of Eu 3+ was observed due to incorporation of Eu 3+ ions into the low-phonon energy BBT crystal site. The local field asymmetric ratios of all the samples were observed greater than unity. The dielectric constant (ε r ), dielectric loss, and dissipation factor values of both the base glass and ceramized samples were found to decrease with increase in frequency. This article is protected by copyright. All rights reserved.

Beschreibung: We report on the materials interaction of gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) in the context of high temperature sintering during manufacturing of anode supported solid oxide fuel cells (AS-SOFC). While ceria-based anodes are expected to show superior electrochemical performance and enhanced sulfur and coking tolerance in comparison to zirconia-based anodes, we demonstrate that the incorporation of a Ni-GDC anode into an ASC with YSZ electrolyte decreases the performance of the ASC by approximately 50% compared to the standard Ni-YSZ cell. The performance loss is attributed to interdiffusion of ceria and zirconia during cell fabrication, which is investigated using powder mixtures and demonstrated to be more severe in the presence of NiO. We examine the physical properties of a GDC-YSZ mixed phase under reducing conditions in detail regarding ionic and electronic conductivity as well as reducibility, and discuss the expected impact of cation intermixing between anode and electrolyte. This article is protected by copyright. All rights reserved.

Beschreibung: The effect of the spark plasma sintering (SPS) process on mullite formation in porcelains was studied using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. SPS affected the kinetics and morphology of formed mullite. After sintering at 1100°C, unlike conventional sintering, SPS promoted the formation of mullite due to the combination of vacuum and applied pressure. Mullite crystal growth was altered by the atmosphere (vacuum), dwell time (0-15 mins), and temperature (1000-1200°C). The applied pressure caused the mullite needles to orient perpendicular to the direction of the applied load. Depending on SPS dwell time, the mullite formed after sintering at 1100°C also had different crystal structure (tetragonal for short dwell time of 0-5min and orthorhombic for a long dwell time of 10-15min). Dissolution of mullite was observed at 1100°C by extending the dwell time by up to 15 minutes and the dissolved mullite re-precipitated on the small needles (~40nm) via Oswald ripening resulting in larger mullite needles (~60nm). This article is protected by copyright. All rights reserved.

Beschreibung: We explored the structure and physical properties of Ge 15 Sb 20 Se 65- x S x (with x=0, 16.25, 32.5, 48.75 and 65) glasses in order to screen the best compositions for the applications in photonics, since the laser damage thresholds in Se-based glasses are too low although their optical nonlinearities are high. We found that, linear and nonlinear refractive index of the glasses decreased, but glass transition temperature T g , optical bandgap E g and the laser damage threshold increased with increasing S content. We further employed Raman scattering and high-resolution X-ray photoelectron spectra (XPS) to probe the structure of the glasses. Through the analysis of the evolution of the different structural units in the glasses, it was concluded that, the heteropolar bonds (Ge-Se/S, Sb-Se/S) were dominated in these glasses. With the increase of chalcogen Se/S ratio, the number of the Se-related chemical bonds (Ge-Se, Sb-Se and Se-Se) increased and that of S-related chemical bond (Ge-S, Sb-S and S-S) decreased gradually, and Ge was prior to bond with S rather than Se. The elemental substitution thus had negligible effect on the glass structure. The change of the physical properties was mainly due to the difference of the strength of the chemical bonds between S-Ge(Sb) and Se-Ge(Sb). This article is protected by copyright. All rights reserved.

Beschreibung: The relaxor material Na 1/2 Bi 1/2 TiO 3 (NBT) is an important basis for the development of lead-free piezoceramics, but still many features of this material are not well understood. Here, we study the kinetics of phase transformations by octahedral tilts and A-cation displacements in NBT by means of density functional theory calculations, employing ab initio molecular dynamics and nudged elastic band calculations. Our results show that the energetic differences between the low temperature rhombohedral, intermediate orthorhombic and other metastable phases are close to the room temperature thermal energy. Therefore, it is likely that above room temperature several octahedral tilt patterns are present simultaneously on the local scale, just because of thermal vibration of the oxygen ions. Octahedral tilt transformations and A-cation displacements show similarly high energy barriers, however, since the vibrational frequency of oxygen is higher, tilt transformations occur more frequently. Further, tilt transformations in which the oxygen octahedra get deformed the least are more probable to occur. We also find that the chemical A-cation order affects energy barriers, influences the coupling between rotational and displacive modes and determines the stability of certain octahedral tilt orders. We conclude that the so-called polar nanoregions in this material result from local octahedral tilt transformations and subsequent A-cation displacements, which are driven by thermal vibration and are mediated by the underlying chemical order. This article is protected by copyright. All rights reserved.

Beschreibung: When adjusting the contrast setting on a television set, we experience a perceptual change in the global image contrast. But how is that statistic computed? We addressed this using a contrast-matching task for checkerboard configurations of micro-patterns in which the contrasts and spatial spreads of two interdigitated components were controlled independently. When the patterns differed greatly in contrast, the higher contrast determined the perceived global contrast. Crucially, however, low contrast additions of one pattern to intermediate contrasts of the other caused a paradoxical reduction in the perceived global contrast. None of the following metrics/models predicted this: max, linear sum, average, energy, root mean squared (RMS), Legge and Foley. However, a nonlinear gain control model, derived from contrast detection and discrimination experiments, incorporating wide-field summation and suppression, did predict the results with no free parameters, but only when spatial filtering was removed. We conclude that our model describes fundamental processes in human contrast vision (the pattern of results was the same for expert and naive observers), but that above threshold—when contrast pedestals are clearly visible—vision's spatial filtering characteristics become transparent, tending towards those of a delta function prior to spatial summation. The global contrast statistic from our model is as easily derived as the RMS contrast of an image, and since it more closely relates to human perception, we suggest it be used as an image contrast metric in practical applications.

Beschreibung: A transient mathematical model was developed for the description of fluid flow, heat transfer and electromagnetic phenomena involved in the production of ferronickel in electric arc furnaces. The key operating variables considered were the thermal and electrical conductivity of the slag and the shape, immersion depth and applied electric potential of the electrodes. It was established that the principal stimuli of the velocities in the slag bath were the electric potential and immersion depth of the electrodes and the thermal and electrical conductivities of the slag. Additionally, it was determined that, under the set of operating conditions examined, the maximum slag temperature ranged between 1756 and 1825 K, which is in accordance with industrial measurements. Moreover, it was affirmed that contributions to slag stirring due to Lorentz forces and momentum forces due to the release of carbon monoxide bubbles from the electrode surface were negligible.

Beschreibung: Reduced graphene oxide–osmium (rGO-Os) hybrid nano dendtrites have been prepared by simple liquid/liquid interface method for the first time. The method involves the introduction of phase-transfered metal organic precursor in toluene phase and GO dispersion in the aqueous phase along with hydrazine hydrate as the reducing agent. Dendritic networks of Os nanoparticles and their aggregates decorating rGO layers are obtained. The substrate shows improved catalytic and surface-enhanced activities comparable with previous reports. The catalytic activity was tested for the reduction of p -nitroaniline into p -phenyldiamine with an excess amount of NaBH 4 . The catalytic activity factors of these hybrid films are 2.3 s –1 g –1 (Os film) and 4.4 s –1 g –1 (rGO-Os hybrid film), which are comparable with other noble metal nanoparticles such as Au, Ag, but lower than Pd-based catalysts. Surface-enhanced Raman spectroscopy (SERS) measurements have been done on rhodamine 6G (R6G) and methylene blue dyes. The enhancement factor for the R6G adsorbed on rGO-Os thin film is 1.0 x 10 5 and for Os thin film is 7 x 10 3 . There is a 14-fold enhancement observed for Os hybrids with rGO. The enhanced catalytic and SERS activities of rGO-Os hybrid thin film prepared by simple liquid/liquid interface method open up new challenges in electrocatalytic application and SERS-based detection of biomolecules.

Beschreibung: In this study, cobalt sulfide (CoS) electrodes are synthesized using various solvents such as water, ethanol and a combination of the two via a facile chemical bath deposition method on Ni foam. The crystalline nature, chemical states and surface morphology of the prepared CoS nanoparticles are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transition electron microscopy. The electrochemical properties of CoS electrodes are also evaluated using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. When used as an electrode for a supercapacitor, CoS prepared with ethanol as a solvent exhibits a capacitance of 41.36 F g –1 at 1.5 A g –1 , which is significantly better than that prepared using water and water/ethanol-based solvents (31.66 and 18.94 F g –1 at 1.5 A g –1 , respectively). This superior capacitance is attributed to the ideal surface morphology of the solvent, which allows for easy diffusion of electrolyte ions into the inner region of the electrode. High electrical conduction enables a high rate capability. These results suggest that CoS nanoparticles are highly promising for energy storage applications as well as photocatalysis, electrocatalysis, water splitting and solar cells, among others. These results show that CoS is a promising positive electrode material for practical supercapacitors.

Beschreibung: Cinnamaldehyde amino acid Schiff base (CAAS) is a new class of safe, bioactive compounds which could be developed as potential antifungal agents for fungal infections. To design new cinnamaldehyde amino acid Schiff base compounds with high bioactivity, the quantitative structure–activity relationships (QSARs) for CAAS compounds against Aspergillus niger ( A. niger ) and Penicillium citrinum (P. citrinum) were analysed. The QSAR models ( R 2 = 0.9346 for A. niger , R 2 = 0.9590 for P. citrinum, ) were constructed and validated. The models indicated that the molecular polarity and the Max atomic orbital electronic population had a significant effect on antifungal activity. Based on the best QSAR models, two new compounds were designed and synthesized. Antifungal activity tests proved that both of them have great bioactivity against the selected fungi.

Beschreibung: The James Clerk Maxwell Telescope (JCMT) has been the world’s most successful single-dish telescope at submillimetre wavelengths since it began operations in 1987. From the pioneering days of single-element photometers and mixers, through to the state-of-the-art imaging and spectroscopic cameras, the JCMT has been associated with a number of major scientific discoveries. Famous for the discovery of ‘SCUBA’ galaxies, which are responsible for a large fraction of the far-infrared background, the JCMT has pushed the sensitivity limits arguably more than any other facility in this most difficult of wavebands in which to observe. Closer to home, the first images of huge discs of cool debris around nearby stars gave us clues to the evolution of planetary systems, further evidence of the importance of studying astrophysics in the submillimetre region. Now approaching the 30th anniversary of the first observations, the telescope continues to carry out unique and innovative science. In this review article, we look back on some of the major scientific highlights from the past 30 years.

Beschreibung: Mixed-matrix membranes (MMMs) were developed by impregnating organofunctionalized nanoadditives within fouling-susceptible polysulfone matrix following the non-solvent induced phase separation (NIPS) method. The facile functionalization of nanoparticles of anatase TiO 2 (nano-TiO 2 ) by using two different organoligands, viz . Tiron and chromotropic acid, was carried out to obtain organofunctionalized nanoadditives, F T -nano-TiO 2 and F C -nano-TiO 2 , respectively. The structural features of nanoadditives were evaluated by X-ray diffraction, X-ray photoelectron spectroscopy, Raman and Fourier transform infrared spectroscopy, which established that Tiron leads to the blending of chelating and bridging bidentate geometries for F T -nano-TiO 2 , whereas chromotropic acid produces bridging bidentate as well as monodentate geometries for F C -nano-TiO 2 . The surface chemistry of the studied membranes, polysulfone (Psf): F T -nano-TiO 2 UF and Psf: F C -nano-TiO 2 UF, was profoundly influenced by the benign distributions of the nanoadditives enriched with distinctly charged sites ( –SO3–H+ ), as evidenced by superior morphology, improved topography, enhanced surface hydrophilicity and altered electrokinetic features. The membranes exhibited enhanced solvent throughputs, viz . 3500–4000 and 3400–4300 LMD at 1 bar of transmembrane pressure, without significant compromise in their rejection attributes. The flux recovery ratios and fouling resistive behaviours of MMMs towards bovine serum albumin indicated that the nanoadditives could impart stable and appreciable antifouling activity, potentially aiding in a sustainable ultrafiltration performance.

Beschreibung: In 1665, Huygens observed that two identical pendulum clocks, weakly coupled through a heavy beam, soon synchronized with the same period and amplitude but with the two pendula swinging in opposite directions. This behaviour is now called anti-phase synchronization. This paper presents an analysis of the behaviour of a large class of coupled identical oscillators, including Huygens' clocks, using methods of equivariant bifurcation theory. The equivariant normal form for such systems is developed and the possible solutions are characterized. The transformation of the physical system parameters to the normal form parameters is given explicitly and applied to the physical values appropriate for Huygens' clocks, and to those of more recent studies. It is shown that Huygens' physical system could only exhibit anti-phase motion, explaining why Huygens observed exclusively this. By contrast, some more recent researchers have observed in-phase or other more complicated motion in their own experimental systems. Here, it is explained which physical characteristics of these systems allow for the existence of these other types of stable solutions. The present analysis not only accounts for these previously observed solutions in a unified framework, but also introduces behaviour not classified by other authors, such as a synchronized toroidal breather and a chaotic toroidal breather.

Beschreibung: To reduce power consumption of transparent oxide-semiconductor thin film transistors, a gate dielectric material with high dielectric constant and low leakage current density is favorable. According to previous study, the bulk TiNb 2 O 7 with outstanding dielectric properties may have an interest in its thin-film form. The optical, chemical states and surface morphology of sol-gel derived TiNb 2 O 7 (TNO) thin films are investigated the effect of post-annealing temperature lower than 500°C, which is crucial to the glass transition temperature. All films possess a transmittance near 80% in the visible region. The existence of non-lattice oxygen in the TNO film is proposed. The peak area ratio of non-lattice oxygen plays an important role in the control of leakage current density of MIM capacitors. Also, the capacitance density and dissipation factor were affected by the indium tin oxide (ITO) sheet resistance at high frequencies. The sample after post-annealing at 300°C and electrode-annealing at 150°C possesses a high dielectric constant (〉30 at 1 MHz) and a low leakage current density (〈1⨯10 -6 A/cm 2 at 1V), which makes it a very promising gate dielectric material for transparent oxide-semiconductor thin film transistors. This article is protected by copyright. All rights reserved.

Beschreibung: InSe, In 2 Se 3 and GaSe are important III-VI semiconductors and are attractive for electronic, optical and optoelectronic applications. This paper reports a fast and cheap way called combustion synthesis to prepare InSe, In 2 Se 3 and GaSe. Bulk samples with relative densities up to 98% are directly produced in a few seconds. The samples show a high phase purity, correct stoichiometry and lamellar crystals larger than 100 μm. By optical absorption, the bandgaps of InSe, In 2 Se 3 and GaSe are determined to be 1.08, 1.24 and 1.75 eV, respectively. This article is protected by copyright. All rights reserved.

Beschreibung: Aiming on the synthesis of a water-free analogue of the mineral cryptophyllite (K 2 CaSi 4 O 10 x5H 2 O) solid-state reactions of a corresponding mixture of K 2 CO 3 , CaCO 3 and SiO 2 were carried out at 800 and 900 °C, respectively. It was possible to ascertain the existence of a previously unknown potassium calcium silicate with composition K 2 CaSi 4 O 10 . Structural investigations were based on single-crystal diffraction experiments. Basic crystallographic data are as follows: triclinic symmetry, space group P1, a = 7.0915(7) Å, b = 8.4211(9) Å, c = 10.2779(12) Å, α = 104.491(10)°, β = 100.570(9)°, γ = 113.738(9)°, V = 515.26(10) Å 3 , Z = 2. Structure solution was performed by direct methods. Subsequent refinement calculations using anisotropic displacement parameters for all atoms converged to a residual of R(|F|) = 0.0355 for 1889 independent reflections with I〉 2σ(I). From a structural point of view K 2 CaSi 4 O 10 belongs to the so-called litidionite family of A’AMSi 4 O 10 compounds for which several natural and synthetic representatives have been described in the literature. Actually, it is the first member where the A’- and A-positions are exclusively occupied by K-ions. Following the nomenclature for oxosilicates K 2 CaSi 4 O 10 can be allocated to the group of the tubular chain silicates. Fundamental building units are loop-branched dreier double chains (running parallel to [100]) which can be described using the following structural formula: {lB,2 1 ∞ }[ 3 Si 8 O 20 ]. Ca-ions are coordinated by five nearest oxygen neighbors in form of distorted trigonal bipyramids. By sharing a common edge two adjacent bipyramids are linked into [Ca 2 O 8 ]-dimers providing linkage between consecutive tubes in the direction of the c-axis. Charge compensation is achieved by the incorporation of the larger potassium ions into cavities of the heteropolyhedral network. Powder X-ray diffraction pattern of the bulk material of the synthesis products revealed that additionally to K 2 CaSi 4 O 10 the 800 °C-sample contains K 8 CaSi 10 O 25 and at least one further, yet unknown crystalline phase. This unspecified substance is also present in the 900 °C-specimen together with K 2 CaSi 4 O 10 and K 2 Ca 4 Si 8 O 21 . Our proof of the existence of K 2 CaSi 4 O 10 represents a further contribution to the description of the ternary system K 2 O-CaO-SiO 2 and corrects earlier phase-analytical studies on this system which is of relevance for applied and technical mineralogy including different types of residual materials such as slags or ashes from biomass combustion. The results of our investigation show that even comparatively simple ternary oxide systems are not as well understood as expected. This article is protected by copyright. All rights reserved.