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Different volume fractions (0.5–4.5 vol%) of carbon nanotubes (CNTs) were used to reinforce a binary Fe50Co soft magnetic alloy. The first method for dispersion involved dry mixing and ball milling of the powder, while the second included wet mixing in dimethylformamide under ultrasonic agitation, drying and then dry ball milling. The powders were consolidated using spark plasma sintering. Tensile test and SEM analyses were performed to characterize the mechanical properties and the fracture surface of the sintered materials. The best magnetic and mechanical properties were achieved using the first method. A maximum enhancement in tensile strength of around 20% was observed in the 0.5 vol% CNT composite with improved elongation compared to the monolithic Fe50Co alloy. In addition, the magnetic properties were enhanced by adding CNTs up to 1 vol%, and an improvement in densification was observed in composites up to 1.5 vol% CNT with respect to monolithic Fe50Co alloy.
Prenatal and early-life environmental exposures play a key role in the development of atopy and allergic disease. The Family Atherosclerosis Monitoring In earLY life Study is a general, population-based Canadian birth cohort that prospectively evaluated prenatal and early-life traits and their association with atopy and/or allergic disease. The study population included 901 babies, 857 mothers and 530 fathers. Prenatal and postnatal risk factors were evaluated through questionnaires collected during the antenatal period and at 1 year. The end points of atopy and allergic diseases in infants were evaluated through questionnaires and skin prick testing. Key outcomes included atopy (24.5%), food allergy (17.5%), cow’s milk allergy (4.8%), wheezing (18.6%) and eczema (16%). The association between infant antibiotic exposure [odds ratio (OR): 2.04, 95% confidence interval (CI): 1.45–2.88] and increased atopy was noted in the multivariate analysis, whereas prenatal maternal exposure to dogs (OR: 0.60, 95% CI: 0.42–0.84) and acetaminophen (OR: 0.68, 95% CI: 0.51–0.92) was associated with decreased atopy. This population-based birth cohort in Canada demonstrated high rates of atopy, food allergy, wheezing and eczema. Several previously reported and some novel prenatal and postnatal exposures were associated with atopy and allergic diseases at 1 year of age.
Our survey of antimicrobial stewardship practices among Rhode Island long-term care facilities demonstrated opportunities to develop formal programs. Results suggest infection preventionists are largely responsible for ensuring appropriate antibiotic use in long-term care facilities and there is a need for increased interdisciplinary access to individuals with antimicrobial stewardship expertise.
The present study aimed to investigate the relationships among bully victimisation and psychosocial health in terms of depression, anxiety, social problems, and perceived wellness. The study also endeavoured to evaluate the gender differences associated with each of these psychosociol variables across varying levels of victimisation. The sample consisted of 180 female and 198 male secondary school students, who each completed a questionnaire package containing scales measuring bully victimisation and psychosocial health. Results indicated that repeated victimisation was associated with heightened levels of depression and anxiety, a greater incidence of social problems, and poorer perceptions of wellbeing. However, being bullied had a greater impact on the perceived wellness of males when compared with females. The results also revealed that social problems may mediate the relationship between depression, perceived wellness, and level of victimisation. It was concluded that bully victimisation is associated with poorer psychosacial health in both male and female adolescents. However, future research should evaluate other potential mediating or moderating relationships between bully victimisation and psychosocial health.
Thin films of Polyvinylidene Fluoride (PVDF) copolymers have been incorporated within ferroelectric field effect transistors, all organic thin film transistor devices (OTFTs), piezoelectric actuators, and recently proposed as the ferroelectric layer in a promising multiferroic tunnel junction configuration . The properties of most of these devices would benefit from reduced thickness and better thickness control of the ferroelectric layer during device processing.
A proven means for fabricating ultrathin films of the PVDF copolymer is the Langmuir-Blodgett (LB) technique. This technique involves dissolving the polymer in a volatile solvent which is then dispersed dropwise onto a purified water subphase, leaving an ultrathin layer of the copolymer on the water surface. The ability to control the thickness on the molecular level is the most prominent feature of this technique.
In some early studies , the minimum thickness of these films was found to be about 5 Angstroms, or roughly the same thickness as the intermolecular spacing of the all-trans β phase for the ferroelectric polymers. Later studies have led to the fabrication of films composed of thicker transfer steps: ∼ 1.8 nm per deposition . The discrepancy is likely explained by the nature of the VDF molecule: it is not an amphiphile.
In this study, we further investigate the properties of Langmuir films of ferroelectric copolymers and discuss the observation of an apparent monolayer phase transition based on abrupt changes observed in the compressibility of the films. The main goal of this project is to discover the extent to which the device properties (like transfer step thickness) of PVDF films can be modified through processing conditions.
The excavation of a large circular dished earthwork near Carnforth,
North Lancashire, in 1982, has revealed a substantial Bronze Age funerary
monument. The earliest structure was a sub-rectangular enclosure of
limestone boulders dated to c. 1740–1640 BC cal. and
associated with parts of two poorly preserved inhumation burials lying on
the previously cleared ground surface. Both burials were accompanied by
typologically early metalwork. The central inhumation was associated with
a flat axe and dagger, suggesting an individual of high status as well as
providing an important link between the early stages of development of
both bronze types. The subsequent overlying cairn of smaller stones
included eleven fairly discrete concentrations of inhumed bone, and seven
of cremated bone and pottery. All this material was extremely
fragmentary, and was probably derived from later re-use of the
Fe-50 wt% Co alloy powders with average particle size of 10 μm were compacted by spark plasma sintering (SPS) at 700, 800, 900 and 950oC by applying 40, 80, 100 MPa uniaxial pressures for 2, 5, 10 minutes. The densities of the samples were found to increase with temperature from 700 to 900oC for constant sintering pressure and time and to decrease for the material sintered at 950oC. The effects of sintering time on density were more significant in samples sintered at 700oC and 800oC than those densified at 900oC. The consequences of small increases in mechanical pressure during sintering on density values were significant for samples sintered at 700oC. The coercivity (Hc) of the compacts decreased significantly with increasing sintering temperature, and with increasing dwell time at sintering temperatures lower than 700oC. The sample sintered at 950oC, which contains the largest grains among the prepared samples and porous microstructure, exhibited the minimum coercivity. Unlike Hc, the remanence (Br) and saturation induction (Bsat) values were more strongly affected by the specimen density than by grain size. Br and Bsat values were found to vary linearly with sintering temperature and pressure owing to increasing density. An increase in soaking time at 800 and 900 oC, although enabling higher density, exhibited contradicting effects on Bsat values. The SPS parameters to obtain maximum density and optimum magnetic properties for Fe-50% Co alloy were found to be 900oC, 80 MPa and 2-5 minutes.
Dopant activation for ion implanted solid phase crystallized (SPC) a-Si:H films, deposited by low temperature PECVD, was investigated. The impact of film thickness, the effect of subsequent hydrogenation, and a possible role for fluorine in this process have been studied.
Plasma-enhanced chemical vapor deposition was used to deposit a-Si:H thin films (∼ 1000 Å) at various temperatures below 300°C on Coming 7059 glass substrates using a silane-based plasma. These films were used as precursor materials to produce solid phase crystallized polycrystalline silicon (poly-Si) by conventional furnace annealing at 600°C in N2 ambient. The precursor a-Si and final poly-Si films were examined using spectroscopic ellipsometry and transmission electron microscopy. Precursor film deposition temperatures were found to affect the void density in the a-Si film and grain size in the resulting poly-Si film with lower deposition temperatures leading to higher void density in the a-Si film and larger grain size in the poly-Si film.
Three approaches to modifying the solid phase crystallization kinetics of amorphous silicon thin films are examined with the goal of reducing the thermal budget and improving the poly-Si quality for thin film transistor applications. The three approaches consist of (1) variations in the PECVD a-Si deposition parameters; (2) the application of pre-fumace-anneal surface treatments; and (3) using both rapid thermal annealing and furnace annealing at different temperatures. We also examine the synergism among these approaches.
Results reveal that (1) film deposition dilution and dilution/temperature changes do not strongly affect crystallization time, but do affect grain size; (2) pre-anneal surface treatments can dramatically reduce the solid phase crystallization thermal budget for diluted films and act synergistically with deposition dilution or dilution/temperature effects; and (3) rapid thermal annealing leads to different crystallization kinetics from that seen for furnace annealing.
Rapid thermal annealing and furnace annealing for the solid phase crystallization of amorphous silicon thin films deposited using PECVD from argon diluted silane have been compared. Results reveal that the crystallization time, the growth time, and the transient time are temperature activated, and that the resulting polycrystalline silicon grain size is inversely proportional to the annealing temperature, for both furnace annealing and rapid thermal annealing. In addition, rapid thermal annealing was found to result in a lower transient time, a lower growth time, a lower crystallization time, and smaller grain sizes than furnace annealing, for a given annealing temperature. Interestingly, the transient time, growth time, and crystallization time activation energies are much lower for rapid thermal annealing, compared to furnace annealing.
We propose two models to explain the observed differences between rapid thermal annealing and furnace annealing.
Nanoindentation is a promising tool for obtaining the elastic properties of thin films. However, no means exists to predict or extrapolate the elastic modulus of the top layer in multilayer systems from experimental data. The mechanical properties of PZT multilayer systems have become increasingly important in applications for MEMS devices. The indentation modulus vs. a/t behaviour of PZT on Pt/SiO2/Si wafer substrate was investigated and compared with a new analytical solution for Herztian indentation of multilayers. Five different PZT film thicknesses were indented (70, 140, 400, 700, 1500 nm), using a 10 μm radius indenter. Good agreement was found between analytical equations and experimental data. However the behaviour of the multilayer system was complex. This makes the deconvolution of film properties difficult for thicknesses less than about 1000 nm.
There is a concerted effort to develop lead-free piezoelectric ceramics. (Na0.5K0.5)NbO3-based ceramics have good electrical properties, and are a potential replacement material for lead zirconate titanate piezoelectric ceramics. In this work a commercial powder based on (Na0.5K0.5)NbO3 with an initial particle size of ∼260 nm was consolidated by spark plasma sintering (SPS). To avoid volatilization, high mechanical pressures were used to minimize the densification temperature. It was found that under a uniaxial pressure of 100 MPa, fully densified compacts can be prepared at 850 °C. Ceramics densified at such a low temperature demonstrate an unusually high remanent polarization (30 μC/cm2) and high d33 (146 pC/N). The improved ferroelectric properties are ascribed to the homogeneous, dense, and submicron grained microstructure achieved.
Research has shown associations between attention-deficit/hyperactivity disorder (ADHD) and erythrocyte long-chain n-3 PUFA (LC n-3 PUFA) levels, with limited evidence for dietary LC n-3 PUFA intake and ADHD. The aims of the present study were to assess dietary PUFA intakes and food sources in children with ADHD, to compare these intakes to previously published Australian National Nutrition Survey (NNS) data and determine any relationships between intakes and ADHD symptoms. Eighty-six 3-d-weighed food records (FR) were analysed from children with ADHD. The median (interquartile range) daily intakes of fatty acids (mg/d) were: linoleic acid (18 : 2n-6), 7797 (6240–12 333); arachidonic acid (20 : 4n-6), 55 (27·0–93); total n-6 PUFA, 7818 (6286–10 662); α-linolenic acid (18 : 3n-3), 1039 (779–1461); EPA (20 : 5n-3), 18 (6·0–32·0); docosapentaenoic acid (22 : 5n-3), 17 (6·3–39·3); DHA (22 : 6n-3), 16 (8·5–445); total LC n-3 PUFA (addition of 20 : 5n-3, 22 : 5n-3 and 22 : 6n-3), 65 (28·3–120·1); total n-3 PUFA, 1151 (876–1592). In comparison to the NNS data, 18 : 3n-3 intakes were higher and 20 : 4n-6 were lower (P < 0·05). Children with ADHD consumed half the amount of fish/seafood, meat and eggs when compared to the NNS (P < 0·05). No significant correlations were found between fatty acids and ADHD symptoms. Children with ADHD met the adequate intake for LC n-3 PUFA, but fell short of other recommendations.
The distribution of Mg and Ni over the octahedrally-coordinated sites M(l,2,3) in Ni-substituted potassic richterite solid solution, AKB(NaCa)c(Mg2.5Ni2.5)Si8O22(OH)2, synthesized at 0.1 GPa/750°C (25 days), has been studied in situ to 700°C by neutron powder diffraction with Rietveld structure refinement. Using a 2.7 g sample it was possible to make short data collections (3 h) at each temperature at intervals of 50° from 50 to700°C and locate the onset of cation exchange. Above 700°C the amphibole decomposes rapidly and so only an on-heating dataset was collected. Unit-cell parameters increase smoothly upon heating, with no discontinuities evident. Site occupancies of M(l), M(2) and M(3) sites were refined from site-scattering values. The initial XNi values of M(l), M(2) and M(3) sites, corresponding to the synthesis temperature of 750°C, are 0.57(1), 0.34(1) and 0.68(2), respectively. Above 400°C, there is initial ordering whereby thermal annealing allows the disordered Mg-Ni distribution of the quenched synthesis product to adjust to be closer to those appropriate for lower temperatures of the heating sequence. This ordering involves the exchange of Mg and Ni between M(l) and M(2), with no significant change in M(3) occupancy. At 700°C, XNi values of the M(l), M(2) and M(3) sites are 0.64(1), 0.27(1) and 0.69(2), respectively. No disordering was observed, due to the short duration of the high-temperature data collections and decomposition at 750°C. The results of this study indicate that divalent cations exchange between octahedral sites in amphiboles in a matter of hours.
The magnetic susceptibility of ordered and partially disordered manganogrunerites (composition and ) has been measured between room temperature and 5 K. The influence of disordering of metal cations over the M(1,2,3) sites of the octahedral ribbon in these amphiboles is to dilute Fe2+ within the ribbon. We observe a reduction in both θp and TN as a function of both increased Mg/(Mg+Fe) and metal cation disorder, linked to a reduction in the strength of magnetic coupling between and within the one-dimensional chains of the structure.
A procedure using nanoindentation with spherical tipped indenters is presented that allows separation of elastic, anelastic, and plastic contributions to the deformation of thin films. The procedure was demonstrated on a range of lanthanum-modified lead titanate (Pb,La)TiO3 (PTL) ferroelectric thin films. Indentation stiffness coefficients ranging from 110 to 147 GPa have been obtained depending on the microstructure and orientation of the PTL films. This coefficient was equivalent to (and so, can be directly compared with) Young's modulus of a nontextured, unpoled ceramic when films do not present preferred orientation. The trends of the anelastic contribution with the thickness, structure, microstructure, and stress level at the film/substrate interface of the films were consistent with it being produced by ferroelastic domain wall movement. Pore compaction was a major mechanism of plastic deformation for the PTL films. Grain size also affected plastic deformation, probably as a consequence of its correlation with intergranular porosity. The technique has a high spatial resolution (contact area < 10 μm2 for the results presented here), which allowed the mechanical homogeneity of the films to be studied and inhomogeneities to be identified from their mechanical response (elastic, anelastic, and plastic).
The crystal structure of a manganoan cummingtonite, composition [M4](Na0.13Ca0.41Mg0.46Mn1.00) [M1,2,3](Mg4.87Mn0.13)(Si8O22)(OH)2, (Z = 2), a = 9.5539(2) Å, b = 18.0293(3) Å, c = 5.2999(1) Å, β = 102.614(2)° from Talcville, New York, has been refined at high temperature using in situ neutron powder diffraction. The P21/m to C2/m phase transition, observed as spontaneous strains +ε1 = −ε2, occurs at ˜107°C. Long-range disordering between Mg2+ and Mn2+ on the M(4) and M(2) sites occurs above 550°C. Mn2+ occupies the M(4) and M(2) sites preferring M(4) with a site-preference energy of 24.6±1.5 kJ mol−1. Disordering induces an increase in XMnM2 and decrease in XMnM4 at elevated temperatures. Upon cooling, the ordered states of cation occupancy are ‘frozen in’ and strains in lattice parameters are maintained, suggesting that re-equilibration during cooling has not taken place.
The phylogenetic affinities of the oyster pathogen Perkinsus
marinus were investigated with morphology, 18S-like rDNA
data and actin sequence data. Morphological investigations revealed that
Perkinsus species do not have a conoid and that
other criteria which have been used to place them in the Apicomplexa are
general to alveolates. When considered separately,
18S-like rDNA and actin data sets each support a closer affinity for
Perkinsus marinus with the dinoflagellates. However,
each of these separate analyses possess their own biases and weaknesses.
Use of the phylogenetic principle of ‘total
evidence’ in which data sets are combined in simultaneous analysis
yielded a more robust hypothesis that is stable both
to character and taxonomic sampling. The resulting cladogram strongly
corroborates the placement of Perkinsus species
with the Dinoflagellida and not with the Apicomplexa.