Magnetocaloric Effect of Micro- and Nanoparticles of Gd5Si4

Materials exhibiting a large magnetocaloric effect (MCE) at or near room temperature are critical for solid-state refrigeration applications. The MCE is described by a change in entropy (ΔSM) and/or temperature (ΔTad) of a material in response to a change in applied magnetic field. Ball milled materials generally exhibit smaller ΔSM values compared to bulk; however, milling broadens the effect, potentially increasing the relative cooling power (RCP). The as-cast Gd5Si4 is an attractive option due to its magnetic transition at 340 K and associated MCE. Investigation of effect of particles size and transition temperature in the binary material, Gd5Si4, can lead to development of functionally graded bulk material with higher MCE and RCP than the traditional bulk materials. A two-step ball-milling process, in which coarse powder of Gd5Si4 was first milled with poly(ethylene glycol) followed by milling in heptane was used to produce fine particles of Gd5Si4 that showed a broad distribution in particle size. Magnetic measurement on the milled sample obtained after washing with water show a decrease in Curie temperature and significant broadening of the magnetic transition. Compared to bulk Gd5Si4, the maximum MCE of the milled samples is also reduced and shifted down by close to 30 K, but the MCE remains substantial over a broader temperature range. The RCP of both milled samples increased 75% from the bulk material

Gadolinium silicide (Gd5Si4) nanoparticles for tuneable broad band microwave absorption

Soft magnetic Gd5Si4 nanoparticles exhibit excellent microwave absorption in the Ku-band (12.4-18 GHz) when dispersed in poly (dimethyl siloxane), PDMS. The minimum experimentally recorded reflection loss (RL) of Gd5Si4-PDMS nanocomposite is −69 dB, with a large bandwidth for a single 6 mm-thick layer. The bandwidth can be further extended by using a novel design where 1 mm-thick layers of the nanocomposite are arranged into a modified pyramid-shaped absorber. Standard electromagnetic (EM) simulations confirm experimental results

Effects of butter naturally enriched with conjugated linoleic acid and vaccenic acid on blood lipids and LDL particle size in growing pigs

<p>Abstract</p> <p>Background</p> <p>Cow milk is a natural source of the cis 9, trans 11 isomer of conjugated linoleic acid (c9,t11-CLA) and trans vaccenic acid (VA). These fatty acids may be considered as functional foods, and the concentration in milk can be increased by e.g. sunflower oil supplementation to the dairy cow feed.</p> <p>The objective of this study was to compare the effects of regular butter with a special butter naturally enriched in c9,t11-CLA and VA on plasma lipids in female growing pigs. The experimental period lasted for three weeks and the two diets provided daily either 5.0 g c9,t11-CLA plus 15.1 g VA or 1.3 g c9,t11-CLA plus 3.6 g VA.</p> <p>Results</p> <p>The serum concentrations of c9,t11-CLA, VA and alpha-linolenic acid were increased and myristic (14:0) and palmitic acid (16:0) were reduced in the pigs fed the CLA+VA-rich butter-diet compared to regular butter, but no differences in plasma concentrations of triacylglycerol, cholesterol, HDL-cholesterol, LDL-cholesterol, LDL particle size distribution or total cholesterol/HDL cholesterol were observed among the two dietary treatment groups.</p> <p>Conclusion</p> <p>Growing pigs fed diets containing butter naturally enriched in about 20 g c9,t11-CLA plus VA daily for three weeks, had increased serum concentrations of alpha-linolenic acid and decreased myristic and palmitic acid compared to pigs fed regular butter, implying a potential benefit of the CLA+VA butter on serum fatty acid composition. Butter enriched in CLA+VA does not appear to have significant effect on the plasma lipoprotein profile in pigs.</p

Dual-barrel conductance micropipet as a new approach to the study of ionic crystal dissolution kinetics

A new approach to the study of ionic crystal dissolution kinetics is described, based on the use of a dual-barrel theta conductance micropipet. The solution in the pipet is undersaturated with respect to the crystal of interest, and when the meniscus at the end of the micropipet makes contact with a selected region of the crystal surface, dissolution occurs causing the solution composition to change. This is observed, with better than 1 ms time resolution, as a change in the ion conductance current, measured across a potential bias between an electrode in each barrel of the pipet. Key attributes of this new technique are: (i) dissolution can be targeted at a single crystal surface; (ii) multiple measurements can be made quickly and easily by moving the pipet to a new location on the surface; (iii) materials with a wide range of kinetics and solubilities are open to study because the duration of dissolution is controlled by the meniscus contact time; (iv) fast kinetics are readily amenable to study because of the intrinsically high mass transport rates within tapered micropipets; (v) the experimental geometry is well-defined, permitting finite element method modeling to allow quantitative analysis of experimental data. Herein, we study the dissolution of NaCl as an example system, with dissolution induced for just a few milliseconds, and estimate a first-order heterogeneous rate constant of 7.5 (±2.5) × 10–5 cm s–1 (equivalent surface dissolution flux ca. 0.5 μmol cm–2 s–1 into a completely undersaturated solution). Ionic crystals form a huge class of materials whose dissolution properties are of considerable interest, and we thus anticipate that this new localized microscale surface approach will have considerable applicability in the future

Attention deficit hyperactivity symptoms predict problematic mobile phone use

Attention-deficit-hyperactivity disorder (ADHD) is the most commonly diagnosed childhood disorder characterised by inattention, hyperactivity/impulsivity, or both. Some of the key traits of ADHD have previously been linked to addictive and problematic behaviours. The aim of the present study was to examine the relationship between problematic mobile phone use, smartphone addiction risk and ADHD symptoms in an adult population. A sample of 273 healthy adult volunteers completed the Adult ADHD Self-Report Scale (ASRS), the Mobile Phone Problem Usage Scale (MPPUS), and the Smartphone Addiction Scale (SAS). A significant positive correlation was found between the ASRS and both scales. More specifically, inattention symptoms and age predicted smartphone addiction risk and problematic mobile phone use. Our results suggest that there is a positive relationship between ADHD traits and problematic mobile phone use. In particular, younger adults with higher level of inattention symptoms could be at higher risk of developing smartphone addiction. The implication of our findings for theoretical frameworks of problematic mobile phone use and clinical practice are discussed

Genomic Organization of Duplicated Major Histocompatibility Complex Class I Regions in Atlantic Salmon (Salmo Salar)

Background: We have previously identified associations between major histocompatibility complex(MHC) class I and resistance towards bacterial and viral pathogens in Atlantic salmon. To evaluate if onlyMHC or also closely linked genes contributed to the observed resistance we ventured into sequencing ofthe duplicated MHC class I regions of Atlantic salmon.Results: Nine BACs covering more than 500 kb of the two duplicated MHC class I regions of Atlanticsalmon were sequenced and the gene organizations characterized. Both regions contained the proteasomecomponents PSMB8, PSMB9, PSMB9-like and PSMB10 in addition to the transporter for antigen processingTAP2, as well as genes for KIFC1, ZBTB22, DAXX, TAPBP, BRD2, COL11A2, RXRB and SLC39A7. TheIA region contained the recently reported MHC class I Sasa-ULA locus residing approximately 50 kbupstream of the major Sasa-UBA locus. The duplicated class IB region contained an MHC class I locusresembling the rainbow trout UCA locus, but although transcribed it was a pseudogene. No other MHCclass I-like genes were detected in the two duplicated regions. Two allelic BACs spanning the UBA locushad 99.2% identity over 125 kb, while the IA region showed 82.5% identity over 136 kb to the IB region.The Atlantic salmon IB region had an insert of 220 kb in comparison to the IA region containing threechitin synthase genes.Conclusion: We have characterized the gene organization of more than 500 kb of the two duplicatedMHC class I regions in Atlantic salmon. Although Atlantic salmon and rainbow trout are closely related,the gene organization of their IB region has undergone extensive gene rearrangements. The Atlanticsalmon has only one class I UCA pseudogene in the IB region while trout contains the four MHC UCA, UDA,UEA and UFA class I loci. The large differences in gene content and most likely function of the salmon andtrout class IB region clearly argues that sequencing of salmon will not necessarily provide informationrelevant for trout and vice versa