Microstructure and microtexture evolution of aluminum alloy 3003 under ultrasonic welding process for embedding SiC fibre

Ultrasonic welding process can be used for bonding metal foils which is the fundament of ultrasonic consolidation (UC). UC process can be used to embed reinforcement fibres such as SiC fibres within an aluminum matrix materials. In this research we are investigating the phenomena occurring in the microstructure of the parts during ultrasonic welding process to obtain better understanding about how and why the process works. High-resolution electron backscatter diffraction (EBSD) is used to study the effects of the vibration on the evolution of microstructure in AA3003. The inverse pole figures (IPF) and the correlated misorientation angle distribution of the mentioned samples are obtained. The characteristics of the crystallographic orientation, the grain structure and the grain boundary are analyzed to find the effect of ultrasonic vibration on the microstructure and microtexture of the bond. The ultrasonic vibration will lead to exceptional refinement of grains to a micron level along the bond area and affect the crystallographic orientation. Ultrasonic vibration results in a very weak texture. Plastic flow occurs in the grain after welding process and there is additional plastic flow around the fibre which leads to the fibre embedding. © 2009 Editorial Board of CHINA WELDING.

Microstrcutural evolution of SiC fibre embedded AA6061 matrix induced by ultrasonic consolidation

Ultrasonic consolidation (UC) uses high frequency (20-40KHz) mechanical vibrations to produce a solid-state metallurgical bond (weld) between metal foils. UC as a novel layered manufacturing technique is used in this research to embed reinforcing members such as silicon carbide fibers into the aluminium alloy 6061's matrices. It is known that UC induce volume and surface effect in the material it is acting on. Both effects are employed in embedding active/passive elements in the metal matrix. Whilst the process and the two effects are used and identified at macro level, what is happening at micro level is unknown and hardly studied. In this research we are investigating the phenomena occurring in the microstructure of the parts during UC process to obtain better understanding about how and why the process works. In this research, high-resolution electron backscatter diffraction is used to study the effects of the UC process on the evolution of microstructure in AA6061 with and without fibre elements. The inverse pole figures (IPF), pole figures (PF) and the correlated misorientation angle distribution of the mentioned samples are obtained. The characteristics of the crystallographic orientation, the grain structure and the grain boundary are analysed to find the effect of ultrasonic vibration and embedding fibre on the microstructure and texture of the bond. The ultrasonic vibration will lead to exceptional refinement of grains to a micron level along the bond area and affect the crystallographic orientation. Additional plastic flow occurs around the fibre which leads to the fibre embedding. © 2008 Materials Research Society.

Using entropy based mean shift filter and modified watershed transform for grain segmentation

Life science research aims to continuously improve the quality and standard of human life. One of the major challenges in this area is to maintain food safety and security. A number of image processing techniques have been used to investigate the quality of food products. In this paper,we propose a new algorithm to effectively segment connected grains so that each of them can be inspected in a later processing stage. One family of the existing segmentation methods is based on the idea of watersheding, and it has shown promising results in practice.However,due to the over-segmentation issue,this technique has experienced poor performance in various applications,such as inhomogeneous background and connected targets. To solve this problem,we present a combination of two classical techniques to handle this issue.In the first step,a mean shift filter is used to eliminate the inhomogeneous background, where entropy is used to be a converging criterion. Secondly,a color gradient algorithm is used in order to detect the most significant edges, and a marked watershed transform is applied to segment cluttered objects out of the previous processing stages. The proposed framework is capable of compromising among execution time, usability, efficiency and segmentation outcome in analyzing ring die pellets. The experimental results demonstrate that the proposed approach is effectiveness and robust.

Evaluation of the effect of wheat aleurone-rich foods on markers of antioxidant status, inflammation and endothelial function in apparently healthy men and women

Observational data show an inverse association between the consumption of whole-grain foods, and inflammation and related diseases. Although the underlying mechanisms are unclear, whole grains, and in particular the aleurone layer, contain a wide range of components with putative antioxidant and anti-inflammatory effects. We evaluated the effects of a diet high in wheat aleurone on plasma antioxidants status, markers of inflammation and endothelial function. In this parallel, participant-blinded intervention, seventy-nine healthy, older, overweight participants (45-65 years, BMI>25 kg/m²) incorporated either aleurone-rich cereal products (27 g aleurone/d), or control products balanced for fibre and macronutrients, into their habitual diets for 4 weeks. Fasting blood samples were taken at baseline and on day 29. Results showed that, compared to control, consumption of aleurone-rich products provided substantial amounts of micronutrients and phytochemicals which may function as antioxidants. Additionally, incorporating these products into a habitual diet resulted in significantly lower plasma concentrations of the inflammatory marker, C-reactive protein (P = 0·035), which is an independent risk factor for CVD. However, no changes were observed in other markers of inflammation, antioxidant status or endothelial function. These results provide a possible mechanism underlying the beneficial effects of longer-term whole-grain intake. However, it is unclear whether this effect is owing to a specific component, or a combination of components in wheat aleurone.

Complex organic molecules in protoplanetary disks

Context. Protoplanetary disks are vital objects in star and planet formation, possessing all the material, gas and dust, which may form a planetary system orbiting the new star. Small, simple molecules have traditionally been detected in protoplanetary disks; however, in the ALMA era, we expect the molecular inventory of protoplanetary disks to significantly increase.

Aims. We investigate the synthesis of complex organic molecules (COMs) in protoplanetary disks to put constraints on the achievable chemical complexity and to predict species and transitions which may be observable with ALMA.

Methods. We have coupled a 2D steady-state physical model of a protoplanetary disk around a typical T Tauri star with a large gas-grain chemical network including COMs. We compare the resulting column densities with those derived from observations and perform ray-tracing calculations to predict line spectra. We compare the synthesised line intensities with current observations and determine those COMs which may be observable in nearby objects. We also compare the predicted grain-surface abundances with those derived from cometary comae observations.

Results. We find COMs are efficiently formed in the disk midplane via grain-surface chemical reactions, reaching peak grain-surface fractional abundances similar to 10(-6)-10(-4) that of the H nuclei number density. COMs formed on grain surfaces are returned to the gas phase via non-thermal desorption; however, gas-phase species reach lower fractional abundances than their grain-surface equivalents, similar to 10(-12)-10(-7). Including the irradiation of grain mantle material helps build further complexity in the ice through the replenishment of grain-surface radicals which take part in further grain-surface reactions. There is reasonable agreement with several line transitions of H2CO observed towards T Tauri star-disk systems. There is poor agreement with HC3(N) lines observed towards LkCa 15 and GO Tau and we discuss possible explanations for these discrepancies. The synthesised line intensities for CH3OH are consistent with upper limits determined towards all sources. Our models suggest CH3OH should be readily observable in nearby protoplanetary disks with ALMA; however, detection of more complex species may prove challenging, even with ALMA "Full Science" capabilities. Our grain-surface abundances are consistent with those derived from cometary comae observations providing additional evidence for the hypothesis that comets (and other planetesimals) formed via the coagulation of icy grains in the Sun's natal disk.

ALMA hints at the presence of two companions in the disk around HD 100546

HD 100546 is a well-studied Herbig Be star-disk system that likely hosts a close-in companion with compelling observational evidence for an embedded protoplanet at 68 AU. We present ALMA observations of the HD 100546 disk which resolve, for the first time, the gas and dust structure at (sub)mm wavelengths. The CO emission (at 345.795 GHz) originates from an extensive molecular disk (390 AU in radius) whereas the continuum emission is more compact (230 AU in radius) suggesting radial drift of the mm-sized grains. The CO emission is similar in extent to scattered light images indicating well-mixed gas and um-sized grains in the disk atmosphere. Assuming an azimuthally-symmetric disk, the continuum visibilities at long baselines (> 100 klambda) are reproduced by a compact ring with a width of 21 AU centered at 26 AU. An outer component is required to fit the short baselines: assuming a flat brightness distribution, the best-fit model is a ring with a width of 75 AU centered at 190 AU. The influence of a companion and protoplanet on the dust evolution is investigated. The companion at 10 AU facilitates the accumulation of mm-sized grains within a compact ring, ~20-30 AU, by ~10 Myr. The injection of a protoplanet at 1 Myr hastens the ring formation (~1.2 Myr) and also triggers the development of an outer ring (~100-200 AU). These observations provide additional evidence for the presence of a close-in companion and hint at dynamical clearing by a protoplanet at 68 AU.

Principles and methods for automated palynology

Pollen grains are microscopic so their identification and quantification has, for decades, depended upon human observers using light microscopes: a labour-intensive approach. Modern improvements in computing and imaging hardware and software now bring automation of pollen analyses within reach. In this paper, we provide the first review in over 15 yr of progress towards automation of the part of palynology concerned with counting and classifying pollen, bringing together literature published from a wide spectrum of sources. We
consider which attempts offer the most potential for an automated palynology system for universal application across all fields of research concerned with pollen classification and counting. We discuss what is required to make the datasets of these automated systems as acceptable as those produced by human palynologists, and present suggestions for how automation will generate novel approaches to counting and classifying pollen that have hitherto been unthinkable.

Outgassing Behavior of C/2012 S1 (ISON) from 2011 September to 2013 June

We report photometric observations for comet C/2012 S1 (ISON) obtained during the time period immediately after discovery (r = 6.28 AU) until it moved into solar conjunction in mid-2013 June using the UH2.2 m, and Gemini North 8 m telescopes on Mauna Kea, the Lowell 1.8 m in Flagstaff, the Calar Alto 1.2 m telescope in Spain, the VYSOS-5 telescopes on Mauna Loa Hawaii and data from the CARA network. Additional pre-discovery data from the Pan STARRS1 survey extends the light curve back to 2011 September 30 (r = 9.4 AU). The images showed a similar tail morphology due to small micron sized particles throughout 2013. Observations at submillimeter wavelengths using the James Clerk Maxwell Telescope on 15 nights between 2013 March 9 (r = 4.52 AU) and June 16 (r = 3.35 AU) were used to search for CO and HCN rotation lines. No gas was detected, with upper limits for CO ranging between 3.5-4.5 × 1027 molecules s-1. Combined with published water production rate estimates we have generated ice sublimation models consistent with the photometric light curve. The inbound light curve is likely controlled by sublimation of CO2. At these distances water is not a strong contributor to the outgassing. We also infer that there was a long slow outburst of activity beginning in late 2011 peaking in mid-2013 January (r ~ 5 AU) at which point the activity decreased again through 2013 June. We suggest that this outburst was driven by CO injecting large water ice grains into the coma. Observations as the comet came out of solar conjunction seem to confirm our models.

Effect of titania addition on yttria-stabilised tetragonal zirconia ceramics sintered at high temperatures

In order to combine the mechanical properties of yttria-stabilised zirconia (ZrO2-3 mol% Y2O3; code Y-ZrO2) with the bioactivity of titania (TiO2), Y-ZrO2-TiO2, green compacts with 0-40vol.% TiO2 were sintered at 1300, 1400, and 1500degreesC for 4h, respectively. The microstructural features such as grains, pores, and phases were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDX). The mechanical properties such as hardness and toughness were also determined using the methods of Vickers indentation and Knoop indentation. All the composites showed the major tetragonal Y-ZrO2 phase regardless of the content of the added TiO2. However, rutile TiO2 phase was obtained at 1300degreesC, whereas zirconium titanate (ZrTi04) phase was found at 1400 and 1500degreesC. The Y-ZrO2-ZrTiO4 Composites sintered at 1500degreesC showed relatively high hardness (860-1000 kg/mm(2)) and toughness (4.0-4.5 MPa m(0.5)), whereas the Y-ZrO2-TiO2 composites sintered at 1300degreesC had slightly lower hardness (720-950kg/mm(2)) and fracture toughness (3.1-3.3 MPa m(0.5)). (C) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Irradiation of oxygen and water ices at by 4 keV singly and doubly charged ions; sputtering and molecular synthesis

The icy surfaces of dust grains in the Interstellar Medium and those of comets, satellites and Kuiper Belt Objects are continuously exposed tophoton and charged particle irradiation. These energetic particles maysputter and induce chemical changes in the ices and the underlyingsurfaces.In the present work 258 nm thick O2 and H2O ices were deposited at 10 K with the thickness measured by a laser interferometer method. Asimple model fit to the reflected laser intensity as measured by aphotodiode detector enabled the refractive index of the ices to bedetermined. The ices were then irradiated with various singly and doublycharged ions such as He+, 13C+, N+, O+ , Ar+, 13C2+, N2+ and O2+ at 4keV. The decrease in ice thickness as a function of ion dose wasmonitored by a laser interferometer and the model used to determine thesputtering yield as shown in Figure 1.In the case of O2 ice thesputtering yields increased with increasing ion mass in good agreementwith a model calculation [Fama, J, Shi, R.A Baragiola, Surface Sci.,602, 156 (2007)]. In the case of O2 ice, O2+ has a significant lowersputtering yield when compared to O+. The sputtering yields for O2 icewere found to be at least 9 times larger compared to those for H2O ice.For H2O ice the sputter yields for C, N and O ions were found todecrease with increasing mass. Doubly charged C, N and O ions which werefound to have the same sputtering yield as the singly charged ionswithin the experimental errors. A preliminary TPD study was carried outusing a QMS to detect the desorbed species from water ice afterirradiation by 6 × 10^15 ions of 13C+ and 13C2+. The formation of13CO and 13CO2 was observed with the yield of 13CO almost of a factor of100 larger than of 13CO2. This is in contrast to our earlier work whereonly CO¬2 was observed.

Ferromagnetism in DyRh and DyRhX (X = Fe, Ni, Co, Gd) thin films

In an effort to achieve large high-field magnetization and increased Curie temperature, polycrystalline DyRh, (DyRh)95X5 and (DyRh)85X15 (X = Fe, Co, Ni, Gd) thin films have been prepared via ultra-high vacuum DC co-sputtering on SiO2 and Si wafers, using Ta as seed and cap material. A body-centred cubic CsCl-like crystal formation (B2 phase) was achieved for DyRh around the equiatomic equilibrium, known from single crystals. The maximum in-plane spontaneous magnetization at T = 4K in fields of μ0H = 5T of was found to be μ0MS,4K = (1.50 ± 0.09)T with a ferromagnetic transition at TC = (5 ± 1)K and a coercivity of μ0HC,4K[D] = (0.010 ± 0.001)T (at T = 4K) for layers deposited on substrates heated to 350°C. Samples prepared at room temperature exhibited poorer texture, smaller grains and less B2-phase content; this did impact on the Curie temperature which was higher compared to those layers with best crystallisation; however the maximal magnetization stayed unaffected. Ferromagnetic coupling was observed in ternary alloys of DyRhGd and DyRhNi with an increased Curie temperature, larger initial permeability, and
high-field magnetization which was best for (DyRh)85Gd15 with μ0MS,4K[Gd15] = (2.10 ± 0.13)T. DyRhFe and DyRhCo showed antiparallel coupling of the spontaneous magnetic moments.

Distal Deposition of Tephra from the Eyjafjallajökull 2010 Summit Eruption

The 2010 Eyjafjallajökull lasted 39 days and had 4 different phases, of which the first and third (14–18 April and 5–6 May) were most intense. Most of this period was dominated by winds with a northerly component that carried tephra toward Europe, where it was deposited in a number of locations and was sampled by rain gauges or buckets, surface swabs, sticky-tape samples and air filtering. In the UK, tephra was collected from each of the Phases 1–3 with a combined range of latitudes spanning the length of the country. The modal grain size of tephra in the rain gauge samples was 25 um, but the largest grains were 100 um in diameter and highly vesicular. The mass loading was equivalent to 8–218 shards cm2, which is comparable to tephra layers from much larger past eruptions. Falling tephra was collected on sticky tape in the English Midlands on 19, 20 and 21st April (Phase 2), and was dominated by aggregate clasts (mean diameter 85 um, component grains <10 um). SEM-EDS spectra for aggregate grains contained an extra peak for sulphur, when compared to control samples from the volcano, indicating that they were cemented by sulphur-rich minerals e.g. gypsum (CaSO4⋅H2O). Air quality monitoring stations did not record fluctuations in hourly PM10 concentrations outside the normal range of variability during the eruption, but there was a small increase in 24-hour running mean concentration from 21–24 April (Phase 2). Deposition of tephra from Phase 2 in the UK indicates that transport of tephra from Iceland is possible even for small eruption plumes given suitable wind conditions. The presence of relatively coarse grains adds uncertainty to concentration estimates from air quality sensors, which are most sensitive to grain sizes <10 um. Elsewhere, tephra was collected from roofs and vehicles in the Faroe Islands (mean grain size 40 um, but 100 um common), from rainwater in Bergen in Norway (23–91 um) and in air filters in Budapest, Hungary (2–6 um). A map is presented summarizing these and other recently published examples of distal tephra deposition from the Eyjafjallajökull eruption. It demonstrates that most tephra deposited on mainland Europe was produced in the highly explosive Phase 1 and was carried there in 2–3 days.

Analysis of deformation behavior and workability of advanced 9Cr-Nb-V ferritic heat resistant steels

Hot compression tests were carried out on 9Cr–Nb–V heat resistant steels in the temperature range of 600–1200 °C and the strain rate range of 10−2–100 s−1 to study their deformation characteristics. The full recrystallization temperature and the carbon-free bainite phase transformation temperature were determined by the slope-change points in the curve of mean flow stress versus the inverse of temperature. The parameters of the constitutive equation for the experimental steels were calculated, including the stress exponent and the activation energy. The lower carbon content in steel would increase the fraction of precipitates by increasing the volume of dynamic strain-induced (DSIT) ferrite during deformation. The ln(εc) versus ln(Z) and the ln(σc) versus ln(Z) plots for both steels have similar trends. The efficiency of power dissipation maps with instability maps merged together show excellent workability from the strain of 0.05 to 0.6. The microstructure of the experimental steels was fully recrystallized upon deformation at low Z value owing to the dynamic recrystallization (DRX), and exhibited a necklace structure under the condition of 1050 °C/0.1 s−1 due to the suppression of the secondary flow of DRX. However, there were barely any DRX grains but elongated pancake grains under the condition of 1000 °C/1 s−1 because of the suppression of the metadynamic recrystallization (MDRX).

Arsenic in Rice Grown in Low-Arsenic Environments in Bangladesh

It has previously been reported that rice grown in regions of Bangladesh with low-arsenic (As) concentrations in irrigation water can have relatively high concentrations of As within their grains. This study aims to determine how widespread this issue is, and determine the seasonal variation in grain As in these regions. Levels of As were measured in shallow tube well (STW) water, soils, and rice grains collected during the Boro (dry) and Aman (wet) seasons from six Upazilas (sub-districts) of Bangladesh where As levels in groundwater were known to be low. In all the Upazilas, the As concentrations in STW water were <50 mu g L-1. The As levels in soil samples collected from the Upazilas ranged between 0.2-4.0 mgkg(-1) in the sam-ples collected during the Boro season, and 0.4-5.7 mg kg(-1) in the samples collected in the Aman season. Levels of As in both Boro and Aman rice grain varied widely: in Boro 0.02-0.45 mg kg(-1), and in Aman 0.01-0.29 mg kg(-1). Additionally, a household survey of dietary habits was also conducted in one Upazila by estimating As ingestion by 15 head female members. On average, the women consumed 3.1 L of water, 1.1 kg of cooked rice, and 42 g dry weight of curry per day. The total As ingestion rates ranged from 31.1-129.3 mu g day(-1) (mean 63.5 mu g kg(-1)). These findings indicate that the major route of As ingestion in low groundwater As areas of Bangladesh is rice, followed by curry and then water.

Identification of quantitative trait loci for rice grain element composition on an arsenic impacted soil:Influence of flowering time on genetic loci

Elements in grain crops such as iron, zinc and selenium are essential in the human diet, whereas elements such as arsenic are potentially toxic to humans. This study aims to identify quantitative trait loci (QTLs) for trace elements in rice grain. A field experiment was conducted in an arsenic enriched field site in Qiyang, China using the Bala x Azucena mapping population grown under standard field conditions. Grains were subjected to elemental analysis by inductively coupled plasma mass spectroscopy. QTLs were detected for the elemental composition within the rice grains, including for iron and selenium, which have previously been detected in this population grown at another location, indicating the stability of these QTLs. A correlation was observed between flowering time and a number of the element concentrations in grains, which was also revealed as co-localisation between flowering time QTLs and grain element QTLs. Unravelling the environmental conditions that influence the grain ionome appears to be complex, but from the results in this study one of the major factors which controls the accumulation of elements within the grain is flowering time.