Ti-SrO metal matrix composites for bone implant materials

Titanium-strontia (Ti-SrO) metal matrix composites (MMCs) with 0, 1, 3 and 5% (weight ratio) of SrO have been fabricated through the powder metallurgy method. Increasing the weight ratio of SrO from 0 to 5%, the compressive strength of Ti-SrO MMCs increased from 982 MPa to 1753 MPa, while the ultimate strain decreased from 0.28 to 0.05. The elastic moduli of Ti-3SrO and Ti-5SrO MMCs were higher than those of Ti and Ti-1SrO MMC samples. Additionally, the micro hardness of Ti-SrO MMCs was enhanced from 59% to 190% with the addition of SrO. The enhanced compression strength and micro hardness of Ti-SrO MMCs were attributed to the Hall-Petch effect and the SrO dispersion strengthening in the Ti matrix. MTS assay results demonstrated that Ti-SrO MMCs with 3% SrO exhibited enhanced proliferation of osteoblast-like cells. Alkaline phosphatase activity of cells was not influenced significantly on the surface of Ti-SrO MMCs compared with pure Ti in a term longer than 10 days. The cell morphology on the Ti-SrO MMCs was observed using confocal microscopy and scanning electron microscopy, which confirmed that the Ti-3%SrO MMCs showed optimal in vitro biocompatibility. This journal is © the Partner Organisations 2014.

Compressibility of a Ti-based alloy with varying amounts of surfactant prepared by high-energy ball milling

The combined effects of varying amounts of surfactant (ethylene bis-stearamide; EBS) and milling time on the compressibility of ball-milled Ti-10Nb-3Mo (wt.%) alloy were investigated. Ball milling process was performed on the elemental powders with different amounts of EBS (0-3. wt.%) for 5 and 10. h, and the ball-milled powders were consolidated by a uniaxial cold pressing in the range of 500-1100. MPa. Results indicated that the addition of surfactant in ball milling process lead to significant changes in particle packing density. The relative density was higher for powders ball milled with larger amounts of EBS and for the shorter milling time. The compressibility of powders was examined by the compaction equation developed by Panelli and Ambrosio Filho. The densification parameter (A) increased with the increasing amount of EBS, and decreased with increasing milling time.

Synthesis of LiFePO4@carbon nanotube core-shell nanowires with a high-energy efficient method for superior lithium ion battery cathodes

A high-energy efficient method is developed for the synthesis of LiFePO4@CNT core-shell nanowire structures. The method consists of two steps: liquid deposition approach to prepare FePO4@CNT core-shell nanowires and solvothermal lithiation to obtain the LiFePO4@CNT core-shell nanowires at a low temperature. The solution phase method can be easily scaled up for commercial application. The performance of the materials produced by this method is evaluated in Li ion batteries. The one-dimensional LiFePO4@CNT nanowires offer a stable and efficient backbone for electron transport. The LiFePO4@CNT core-shell nanowires exhibit a high capacity of 132.8 mAh g^-1 at a rate of 0.2C, as well as high rate capability (64.4 mAh g^-1 at 20C) for Li ion storage.

Metabolic rate and thermal conductance of lemmings from high-arctic Canada and Siberia

The arctic climate places high demands on the energy metabolism of its inhabitants. We measured resting (RMR) and basal metabolic rates (BMR), body temperatures, and dry and wet thermal conductances in summer morphs of the lemmings Dicrostonyx groenlandicus and Lemmus trimucronatus in arctic Canada, and the BMR of D. torquatus, D. groenlandicus, L. sibiricus, L. bungei and L. trimucronatus in Siberia. In contrast to previous studies the data were collected on animals that had spent only a limited time in captivity. All parameters were analysed in relation to the variations in body mass (20-90 g). Body temperature and BMR were lower in D. groenlandicus than L. trimucronatus, which coincides with greater longevity in the former species. Wet and dry thermal conductances of both species were similar and comparable with those of other Myomorpha (mouse-type rodents), indicating no evidence for a previously claimed lower thermal conductance in lemmings. BMR in lemmings appeared to be higher than in other Arvicolidae (voles, lemmings and muskrats), which could relate to their typically high-latitude distribution. However, the more southerly living Lemmus species had higher BMR than the more northerly living Dicrostonyx species, which may be explained by the former having a relatively low-quality diet.

Simultaneous improvement in the strength and corrosion resistance of Al via high-energy ball milling and Cr alloying

The corrosion resistance and mechanical properties of nanocrystalline aluminium (Al) and Al-20. wt.%Cr alloys, synthesized by high-energy ball milling followed by spark plasma sintering, were investigated. Both alloys exhibited an excellent combination of corrosion resistance and compressive yield strength, which was attributed to the nanocrystalline structure, extended solubility, uniformly distributed fine particles, and homogenous microstructure induced by high-energy ball milling. This work demonstrates the possibilities of developing ultra-high strength Al alloys with excellent corrosion resistance, exploiting conventionally insoluble elements or alloying additions via suitable processing routes.

Wave exposure as a predictor of benthic habitat distribution on high energy temperate reefs

The new found ability to measure physical attributes of the marine environment at high resolution across broad spatial scales has driven the rapid evolution of benthic habitat mapping as a field in its own right. Improvement of the resolution and ecological validity of seafloor habitat distribution models has, for the most part, paralleled developments in new generations of acoustic survey tools such as multibeam echosounders. While sonar methods have been well demonstrated to provide useful proxies of the relatively static geophysical patterns that reflect distribution of benthic species and assemblages, the spatially and temporally variable influence of hydrodynamic energy on habitat distribution have been less well studied. Here we investigate the role of wave exposure on patterns of distribution of near-shore benthic habitats. A high resolution spectral wave model was developed for a 624 km2 site along Cape Otway, a major coastal feature of western Victoria, Australia. Comparison of habitat classifications implemented using the Random Forests algorithm established that significantly more accurate estimations of habitat distribution were obtained by including a fine-scale numerical wave model, extended to the seabed using linear wave theory, than by using depth and seafloor morphology information alone. Variable importance measures and map interpretation indicated that the spatial variation in wave-induced bottom orbital velocity was most influential in discriminating habitat classes containing the canopy forming kelp Ecklonia radiata, a foundation kelp species that affects biodiversity and ecological functioning on shallow reefs across temperate Australasia. We demonstrate that hydrodynamic models reflecting key environmental drivers on wave-exposed coastlines are important in accurately defining distributions of benthic habitats. This study highlights the suitability of exposure measures for predictive habitat modeling on wave-exposed coastlines and provides a basis for continuing work relating patterns of biological distribution to remotely-sensed patterns of the physical environment.

Corrosion behaviour and hardness of in situ consolidated nanostructured Al and Al-Cr alloys produced via high-energy ball milling

This paper presents a hypothesis and its experimental validation that simultaneous improvement in the hardness and corrosion resistance of aluminium can be achieved by the combination of suitable processing route and alloying additions. More specifically, the corrosion resistance and hardness of Al- xCr (x= 0-10 wt.%) alloys as produced via high-energy ball milling were significantly higher than pure Al and AA7075-T651. The improved properties of the Al- xCr alloys were attributed to the Cr addition and high-energy ball milling, which caused nanocrystalline structure, extended solubility of Cr in Al, and uniformly distributed fine intermetallic phases in the Al-Cr matrix.

Not so fast: swimming behavior of sailfish during predator-prey interactions using high-speed video and accelerometry

Billfishes are considered among the fastest swimmers in the oceans. Despite early estimates of extremely high speeds, more recent work showed that these predators (e.g., blue marlin) spend most of their time swimming slowly, rarely exceeding 2 m s(-1). Predator-prey interactions provide a context within which one may expect maximal speeds both by predators and prey. Beyond speed, however, an important component determining the outcome of predator-prey encounters is unsteady swimming (i.e., turning and accelerating). Although large predators are faster than their small prey, the latter show higher performance in unsteady swimming. To contrast the evading behaviors of their highly maneuverable prey, sailfish and other large aquatic predators possess morphological adaptations, such as elongated bills, which can be moved more rapidly than the whole body itself, facilitating capture of the prey. Therefore, it is an open question whether such supposedly very fast swimmers do use high-speed bursts when feeding on evasive prey, in addition to using their bill for slashing prey. Here, we measured the swimming behavior of sailfish by using high-frequency accelerometry and high-speed video observations during predator-prey interactions. These measurements allowed analyses of tail beat frequencies to estimate swimming speeds. Our results suggest that sailfish burst at speeds of about 7 m s(-1) and do not exceed swimming speeds of 10 m s(-1) during predator-prey interactions. These speeds are much lower than previous estimates. In addition, the oscillations of the bill during swimming with, and without, extension of the dorsal fin (i.e., the sail) were measured. We suggest that extension of the dorsal fin may allow sailfish to improve the control of the bill and minimize its yaw, hence preventing disturbance of the prey. Therefore, sailfish, like other large predators, may rely mainly on accuracy of movement and the use of the extensions of their bodies, rather than resorting to top speeds when hunting evasive prey.

Rank-based Image watermarking method with high embedding capacity and robustness

This paper presents a novel rank-based method for image watermarking. In the watermark embedding process, the host image is divided into blocks, followed by the 2-D discrete cosine transform (DCT). For each image block, a secret key is employed to randomly select a set of DCT coefficients suitable for watermark embedding. Watermark bits are inserted into an image block by modifying the set of DCT coefficients using a rank-based embedding rule. In the watermark detection process, the corresponding detection matrices are formed from the received image using the secret key. Afterward, the watermark bits are extracted by checking the ranks of the detection matrices. Since the proposed watermarking method only uses two DCT coefficients to hide one watermark bit, it can achieve very high embedding capacity. Moreover, our method is free of host signal interference. This desired feature and the usage of an error buffer in watermark embedding result in high robustness against attacks. Theoretical analysis and experimental results demonstrate the effectiveness of the proposed method.

High atmospheric temperatures and 'ambient incubation' drive embryonic development and lead to earlier hatching in a passerine bird

Tropical and subtropical species typically experience relatively high atmospheric temperatures during reproduction, and are subject to climate-related challenges that are largely unexplored, relative to more extensive work conducted in temperate regions. We studied the effects of high atmospheric and nest temperatures during reproduction in the zebra finch. We characterized the temperature within nests in a subtropical population of this species in relation to atmospheric temperature. Temperatures within nests frequently exceeded the level at which embryo's develop optimally, even in the absence of parental incubation. We experimentally manipulated internal nest temperature to demonstrate that an average difference of 6°C in the nest temperature during the laying period reduced hatching time by an average of 3% of the total incubation time, owing to 'ambient incubation'. Given the avian constraint of laying a single egg per day, the first eggs of a clutch are subject to prolonged effects of nest temperature relative to later laid eggs, potentially increasing hatching asynchrony. While birds may ameliorate the negative effects of ambient incubation on embryonic development by varying the location and design of their nests, high atmospheric temperatures are likely to constitute an important selective force on avian reproductive behaviour and physiology in subtropical and tropical regions, particularly in the light of predicted climate change that in many areas is leading to a higher frequency of hot days during the periods when birds breed.

Progress achieved in restricting the marketing of high-fat, sugary and salty food and beverage products to children

In May 2010, 192 Member States endorsed Resolution WHA63.14 to restrict the marketing of food and non-alcoholic beverage products high in saturated fats, trans fatty acids, free sugars and/or salt to children and adolescents globally. We examined the actions taken between 2010 and early 2016 - by civil society groups, the World Health Organization (WHO) and its regional offices, other United Nations (UN) organizations, philanthropic institutions and transnational industries - to help decrease the prevalence of obesity and diet-related noncommunicable diseases among young people. By providing relevant technical and policy guidance and tools to Member States, WHO and other UN organizations have helped protect young people from the marketing of branded food and beverage products that are high in fat, sugar and/or salt. The progress achieved by the other actors we investigated appears variable and generally less robust. We suggest that the progress being made towards the full implementation of Resolution WHA63.14 would be accelerated by further restrictions on the marketing of unhealthy food and beverage products and by investing in the promotion of nutrient-dense products. This should help young people meet government-recommended dietary targets. Any effective strategies and actions should align with the goal of WHO to reduce premature mortality from noncommunicable diseases by 25% by 2025 and the aim of the UN to ensure healthy lives for all by 2030.

Bimodal magneto-luminescent dysprosium (DyIII)-potassium (KI)-oxalate framework: magnetic switchability with high anisotropic barrier and solvent sensing

We report synthesis, characterization, and properties of a multifunctional oxalate framework, {KDy(C₂O₄)₂(H₂O)₄}_n (1) (C₂O₄^2- = oxalate dianion) composed of two absolutely different metal ions in terms of their size, charge, and electronic configuration. Dehydrated framework (1′) exhibits permanent porosity and interesting solvent (H₂O, MeOH, CH₃CN, and EtOH) vapor sorption characteristics based on specific interactions with unsaturated alkali metal sites on the pore surface. Compound 1 shows solvent responsive bimodal magnetic and luminescence properties related to the DyIII center. Compound 1 exhibits reversible ferromagnetic to antiferromagnetric phase transition upon dehydration and rehydration, hitherto unknown for any lanthanide based coordination polymer or metal-organic frameworks. Both the compounds 1 and 1′ exhibit slow magnetic relaxation with very high anisotropic barrier (417 ± 9 K for 1 and 418 ± 7 K for 1′) which has been ascribed to the single ion magnetic anisotropy of the Dy^III centers. Nevertheless, compound 1 shows a metal based luminescence property in the visible region and H₂O molecules exhibit the strongest quenching effect compared to other solvents MeOH, MeCN, and EtOH, evoking 1′ as a potential H₂O sensor.