Magnetostatic bias in multilayer microwires: theory and experiments

The hysteresis curves of multilayer microwires consisting of a soft magnetic nucleus, intermediate non-magnetic layers, and an external hard magnetic layer are investigated. The magnetostatic interaction between magnetic layers is proved to give rise to an antiferromagnetic-like coupling resulting in a magnetostatic bias in the hysteresis curves of the soft nucleus. This magnetostatic biasing effect is investigated in terms of the microwire geometry. The experimental results are interpreted considering an analytical model taking into account the magnetostatic interaction between the magnetic layers.Comment: 6 pages, 7 figure

Fabrication and magnetic properties of hard/soft magnetostatically coupled FePt/FeNi multilayer microwires

3 pages, 5 figures.-- PACS: 75.70.Cn; 75.60.Ej; 75.50.Ww; 81.15.Pq; 68.65.Ac; 81.40.EfA family of multilayer microwires with hard/soft biphase magnetic behavior is here introduced. The microwires consist of a Fe63Pt27Si10 hard magnetic nucleus and a Fe20Ni80 soft outer shell separated by an intermediate insulating Pyrex glass microtube. The precursor FePtSi glass-coated microwire is fabricated by quenching and drawing technique, and its L10 hard magnetic phase is grown by postannealing treatment technique. The polycrystalline FeNi soft magnetic outer shell has been deposited by electroplating. The analysis of the low-field hysteresis loops of the FeNi soft phase after premagnetizing until near magnetic saturation provides information about the magnetostatic coupling between phases. The FeNi magnetization curve is shifted toward positive field when the FePt remanent magnetization is positive and vice versa. A systematic analysis of the magnetostatic coupling and the corresponding bias field arising from uncompensated poles of the premagnetized FePt hard phase has been performed. The strength of the bias field is shown to increase with the reduction of thickness of the FeNi layer. These magnetostatically coupled biphase systems are thought to be of large potential interest as sensing elements in sensor devices.The work has been developed under the Project No. MAT2004-00150 supported by the Spanish Ministry of Education and Science, MEC. J. T. acknowledges a FPU program fellowship from MEC.Peer reviewe

Burden and associated factors for caregivers of the elderly in a developing country

The elderly population in South Asia is growing. In Pakistan trained caregivers are scarce and culturally not acceptable. This study assessed the level of stress experienced by caregivers of the elderly and determined the association of care giving burden with different characteristics of the elderly. A cross-sectional, questionnaire based study was conducted using nonprobability purposive sampling. All consenting participants aged 60 years and above needing help with at least one activity of daily living or two instrumental activities of daily living were included. 350 participants were assessed for perceived care giver burden. Care providers were mostly female (68.9%). Half (50.3%) of the caregivers had a positive score on a perceived care burden scale. Financial impact had a strong correlation (0.79) with perceived caregiver burden. Higher dependency levels of a physical and cognitive nature posed greater burden on caregivers. Behavioural issues of the elderly such as verbal abuse and difficulty sleeping were predictors of a higher caregiver burden. Caregiver burden is a significant issue for those caring for elderly family members in Karachi, Pakistan

Effect of stocking density and protein/fat ratio of the diet on growth of Dover sole (Solea solea)

250 soles (30g initial weight) were randomly placed in 12 experimental tanks at the Discizia's aquaculture marine station. They were reared at 2 different stocking densities (2.3 and 1.3kg/m2 corresponding to 40% and 25% of the bottom surface area covered by fish) and fed on 2 diets with different protein/fat ratio (50% and 54% crude protein and 21% and 18% total lipid, respectively for diets A and B) with triplicate tanks per treatment. The trial lasted 120 days. Fish stocked at the lower density resulted in significantly higher weight gain than fish reared at 2.3 kg/m2 (29.0±7.3 g vs 20.3±8.0g; P<0.01) with a specific growth rate (SGR) of 0.54±0.09 and 0.42±0.13, respectively. Feed conversion rate (FCR) was improved at the lower density (1.8 vs 2.4, P<0.01). The chemical composition of the test diets significantly affected the growth performance of sole. Diet B led to a higher final weight (59.7 vs 50.8g; P<0.01) and better feed utilisation (FCR: 1.8 vs 2.4, P<0.01). These results confirm the necessity to ensure an adequate space for the growing sole and suggest the need for high protein diets to meet sole's requirements

Guidelines For Reducing The Noise Level Of A Centrifugal Air Compressor Installation

Tutorialpg. 203-212This paper will review the best practices for installation of a centrifugal air compressor without a sound enclosure to obtain the best acoustic environment for reduced operating noise levels. An overview of the noise sources associated with a centrifugal air compressor will be discussed along with the noise attenuation techniques. Moreover, proper selection and installation of accessory hardware associated with the compressor installation will be addressed, since the accessory hardware can often generate higher noise levels than the compressor if not selected and installed correctly. Guidelines for valve sizing, proper lagging of piping and valves for noise reduction, drain line noise attenuation, inlet silencer selection, discharge silencer selection and silencer installation will also be explored. The refining, petrochemical, oil and gas, automotive, steel, electronic and industrial applications utilize centrifugal air compressors to provide utility air to support manufacturing their processes. They are often purchased to meet a specified noise level based on customer site requirements. Compressors that meet the noise requirement without using a complete sound enclosure are preferred. This is due to both the high cost associated with sound enclosures and because sound enclosures make access to the compressor difficult for maintenance. Figure 1 shows a typical centrifugal air compressor package for a refinery application. Proper site development is important for reduced noise levels while the equipment is in operation. Outdoor installations do not exactly replicate a Free Field noise environment; indoor installations are often reverberant in nature because of building construction. In any case, when the compressor is in operation, the noise level measured with a sound level meter is often higher than the actual compressor generated noise. This paper will provide guidelines on how to achieve compressor installation noise objectives

Novel 3D printable bio-based and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) microspheres for selective laser sintering applications

Selective laser sintering (SLS) has become the most popular additive manufacturing process due to its high accuracy, productive efficiency, and surface quality. However, currently there are still very few commercially available polymeric materials suitable for this technique. This research work focused on the fabrication and characterization of bio-based and biodegradable microspheres obtained by oil-in-water emulsion solvent evaporation, starting from a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) biopolymer matrix. First, the fabrication parameters were optimized to improve the morphological, thermal, and flowability properties of the synthetized microspheres. Once the best production conditions were established, the PHBH microspheres were further used to study their effective 3D printability on an SLS 3D printer using geometries varying from simple shapes to architectures with more complex internal patterns. The results of this research revealed that PHBH has promising applicability for the SLS technique. This study undertook the first step toward broadening the range of polymeric materials for this additive manufacturing technology. These findings will contribute to a greater and wider dissemination of the SLS technique in the future, as well as they will bring this manufacturing process closer to applications, such as the biomedical sector, where the use of biodegradable and biocompatible materials can add value to the final application

Growth modes of nanoparticle superlattice thin films

We report about the fabrication and characterization of iron oxide nanoparticle thin film superlattices. The formation into different film morphologies is controlled by tuning the particle plus solvent-to-substrate interaction. It turns out that the wetting vs. dewetting properties of the solvent before the self-assembly process during solvent evaporation plays a major role to determine the resulting film morphology. In addition to layerwise growth also three-dimensional mesocrystalline growth is evidenced. The understanding of the mechanisms ruling nanoparticle self-assembly represents an important step toward the fabrication of novel materials with tailored optical, magnetic or electrical transport properties

Domain-wall structure in thin films with perpendicular anisotropy: Magnetic force microscopy and polarized neutron reflectometry study

Ferromagnetic domain patterns and three-dimensional domain-wall configurations in thin CoCrPt films with perpendicular magnetic anisotropy were studied in detail by combining magnetic force microscopy and polarized neutron reflectometry with micromagnetic simulations. With the first method, lateral dimension of domains with alternative magnetization directions normal to the surface and separated by domain walls in 20-nm-thick CoCrPt films were determined in good agreement with micromagnetic simulations. Quantitative analysis of data on reflectometry shows that domain walls consist of a Bloch wall in the center of the thin film, which is gradually transformed into a pair of Néel caps at the surfaces. The width and in-depth thickness of the Bloch wall element, transition region, and Néel caps are found consistent with micromagnetic calculations. A complex structure of domain walls serves to compromise a competition between exchange interactions, keeping spins parallel, magnetic anisotropy orienting magnetization normal to the surface, and demagnetizing fields, promoting in-plane magnetization. It is shown that the result of such competition strongly depends on the film thickness, and in the thinner CoCrPt film (10 nm thick), simple Bloch walls separate domains. Their lateral dimensions estimated from neutron scattering experiments agree with micromagnetic simulations.Microelectronics Advanced Research Corporation (MARCO)United States. Defense Advanced Research Projects Agenc

Comparative Efficiency of Soil and Foliar Applied Zinc in Improving Yield and Yield Components of Wheat (Triticum aestivum L.) Variety Kiran-95

A field study was undertaken to evaluate the comparative efficacy of zinc application through soil and foliar spray on growth and yield of wheat variety Kiran-95 at Soil Chemistry Section, Agriculture Research Institute, Tandojam during Rabi 2013-14. The experiment was laid out in three replicated randomized complete block design. The treatments comprised Control (No Zinc), Soil applied Zinc 5.0 kg ha-1 at tillering stage, Soil applied Zinc 10.0 kg ha-1 at tillering stage, Soil applied Zinc 5.0 kg ha-1 at tillering + 5.0 kg ha-1 at booting stage, Foliar applied Zinc 0.2% at tillering stage, Foliar applied Zinc 0.4% at tillering and Foliar applied Zinc 0.2% at tillering stage + 0.2% at booting stage. The statistical analysis of data suggested that soil and foliar applied zinc affected significantly (P&lt;0.05) growth and yield traits of wheat variety Kiran-95. The results illustrated that Soil applied Zinc 5.0 kg ha-1 at tillering + 5.0 kg ha-1 at booting stage produced maximum plant height (99.0 cm), tillers (410.7 m-2), spike length (13.1 cm), spikelets per spike (23.0), grains per  spike (45.1), seed index (43.4 g), biological yield (9354.4 kg ha-1) and grain yield (5123.4 kg ha-1), closely followed by Foliar applied Zinc 0.2% at tillering stage + 0.2% at booting stage with 97.6 cm plant height, 408.8 tillers m-2, 13.0 cm spike length, 22.8 spikelets per spike, 45.0 grains per spike, 43.2 g seed index, 9273.4 kg ha-1 biological yield and 5080.7 kg ha-1 grain yield. The performance of wheat variety Kiran-95 ranked 3rd, 4th, 5th and 6th almost in all the growth and yield parameters particularly grain yield (kg ha-1) when fertilized with Soil applied Zinc 10.0 kg ha-1 at tillering stage, Foliar applied Zinc 0.4% at tillering, Soil applied Zinc 5.0 kg ha-1 at tillering stage and Foliar applied Zinc 0.2% at tillering stage.  However, minimum growth and yield traits were registered in Control (No Zinc). Furthermore, the results concluded that although numerically maximum growth and yield values were recorded in Soil applied Zinc 5.0 kg ha-1 at tillering + 5.0 kg ha-1 at booting stage but statistically the differences between Soil applied Zinc 5.0 kg ha-1 at tillering + 5.0 kg ha-1 at booting stage and Foliar applied Zinc 0.2% at tillering stage + 0.2% at booting stage were non-significant. Hence, Foliar applied Zinc 0.2% at tillering stage + 0.2% at booting stage were found the most economical treatment for obtaining optimum yield of wheat variety Kiran-95. Keywords: Wheat, Comparative Efficiency, Soil, Foliar, Zinc, Improving Yield and Yield Component