178 research outputs found
Some aspects of Magnetic Force Microscopy of hard magnetic films
International audienceA number of aspects of magnetic force microscopy (MFM) specific to the imaging of hard magnetic films have been studied. Firstly, we show that topographic images made in tapping mode with probes characterized by the moderate cantilever stiffness usual for MFM (1â4 N/m), contain artifacts due to strong probe-sample interactions which lead to probe retraction. As a result, stiffer cantilevers (e.g. 40 N/m) are better adapted to characterizing such hard magnetic films. Secondly, imaging with probes coated by a hard magnetic film leads to phase maps which show a twofold symmetry, with paired dark/light contrast on opposite domain edges along the direction of the cantilever. This is due to the tilt of the direction of tip magnetizaiton and direction of oscillation, with respect to the sample normal. Thirdly, due to the long-range nature of the stray field produced by hard magnetic films containing micron-sized domains, MFM phase contrast reflects the stray field itself, as opposed to that of its spatial derivatives, as is generally the case in MFM
Structural, magnetic and mechanical properties of 5 ”m thick SmCo films for use in Micro-Electro-Mechanical-Systems
5”m thick SmCo films were deposited onto Si substrates using triode sputtering. A study of the influence of deposition temperature (Tdep †600°C) on the structural, magnetic and mechanical properties has shown that optimum properties (highest degree of in-plane texture, maximum in-plane coercivity and remanence (1.3 and 0.8 T, respectively), no film peel-off) are achieved for films deposited at the relatively low temperature of 350°C. This temperature is compatible with film integration into Micro-Electro-Mechanical-Systems (MEMS). The deposition rate was increased from 3.6 to 18 ”m/h by increasing the surface area of the target from 7 to 81 cm2. Mechanically stable films could be prepared by deposition onto pre-patterned films or deposition through holes in a mask
Combined magnetic and chemical patterning for neural architectures
In vitro investigation of neural architectures requires cell positioning. For
that purpose, micro-magnets have been developed on silicon substrates and
combined with chemical patterning to attract cells to adhesive sites and keep
them there during incubation. We have shown that the use of micro-magnets
allows to achieve a high filling factor (~90%) of defined adhesive sites in
neural networks and prevents migration of cells during growth. This approach
has great potential for neural interfacing by providing accurate and
time-stable coupling with integrated nanodevices
Implementing a rapid fetal exome sequencing service: What do parents and health professionals think?
OBJECTIVES: Prenatal exome sequencing (pES) for the diagnosis of fetal abnormalities is being introduced more widely in clinical practice. Here we explore parents' and professionals' views and experiences of pES, to identify perceived benefits, concerns, and support needs. METHODS: Semi-structured interviews were conducted with 11 parents and 20 health professionals (fetal medicine and clinical genetics) with experience of rapid pES prior to implementation in the English National Health Service. Interviews were transcribed verbatim and analysed thematically. RESULTS: Parents and professionals were largely positive about pES, emphasising clinical and psychosocial benefits of a timely, definitive diagnosis in pregnancy. Concerns included parental anxiety related to the timing of pES results or uncertain findings, a need for guidelines for case selection and reporting, and ensuring sufficient capacity for counselling, phenotyping and variant interpretation. Professionals were concerned non-genetics professionals may not be equipped to counsel parents on the complexities of pES. CONCLUSION: These findings highlight important issues for clinical implementation of pES. Expert counselling is required to enable parents to make informed decisions during a stressful time. To achieve this, professionals need further education and training, and fetal medicine and genetics services must work closely together to ensure parental understanding and appropriate support
Hard Ferromagnets as a New Perspective on Materials for Thermomagnetic Power Generation Cycles
We consider the ways in which magnetically hard materials can be used as the
working materials in thermomagnetic power generation (TMG) cycles in order to
expand the area in the magnetisation vs. applied field () plane available
for energy conversion. There are 3 parts to this Perspective. First,
experiments on commercially available hard ferrites reveal that, while these
materials are not yet good TMG candidates, hard ferromagnets with higher
thermal conductivity and a greater change of magnetization with temperature
could outperform existing TMG materials. Second, computational results indicate
that biasing a soft magnet with a hard ferromagnet is essentially equivalent to
shifting the loop by an amount proportional to the field of the biasing
magnet. Work outputs under biased conditions show a substantial improvement
over unbiased cycles, but experimental verification is needed. Third, we
discuss the rationale for exploring artificial spin reorientation materials as
novel TMG working materials.Comment: 13 pages, 7 figure
Preparation of microstructured and nanostructured magnetic materials by mechanical deformation
Abstract A novel hydrostatic extrusion process utilising sacrificial Al billets has been developed to allow the size reduction by deformation of samples of various cross-sectional shape (e.g. square, rectangular). Cyclic deformation of a stack of submm thick foils of magnetic and non-magnetic metals (Fe and Ag), combining extrusion with cold-rolling, has been used to prepare nanoscaled multilayered structures. 6% GMR was measured in the Fe/Ag multilayer system, after 4 deformation cycles, in the current-in-plane geometry at 4 K. Extrusion was also used to prepare micro-composite Sm/Fe structures which were subsequently heat treated to form magnetostrictive SmFe 2 rods with room temperature magnetostriction values as large as Ă800 ppm in the extrusion direction.
Rapid Prototyping of Reconfigurable Microfluidic Channels in Undercooled Metal Particle-Elastomer Composites
Conventional fabrication of microfluidic channels/devices are faced with challenges such as single use channels and/or significant time consumption. We propose a flexible platform for fabricating microfluidic channels simply through indentation on a smart compositeâthe so-called ST3R (Stiffness tuning through thermodynamic relaxation) composite. The application of ST3R composite allows rapid fabrication of microfluidic channels by hand or with a prefabricated stamp, and precise prototyping of complex designs using a 2D plotter. Indenter geometry, applied stress, filler loading, and number of repeated indentations affect channel dimensions and/or shape. These channels further exhibit; i) Substantial improvement against swelling by organic solvent, in part due to the high modulus of the solidified metal network. ii) Channel reconfigurability by heating the solidified undercooled metals. ST3R composite slabs have the potential to serve as microfluidic âbreadboardsâ, from which complex channels can be integrated in a flexible manner
Benefits for Type 2 Diabetes of Interrupting Prolonged Sitting With Brief Bouts of Light Walking or Simple Resistance Activities
OBJECTIVE To determine whether interrupting prolonged sitting with brief bouts of light-intensity walking (LW) or simple resistance activities (SRA) improves postprandial cardiometabolic risk markers in adults with type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS In a randomized crossover trial, 24 inactive overweight/obese adults with T2D (14 men 62 ± 6 years old) underwent the following 8-h conditions on three separate days (with 6â14 days washout): uninterrupted sitting (control) (SIT), sitting plus 3-min bouts of LW (3.2 km · hâ1) every 30 min, and sitting plus 3-min bouts of SRA (half-squats, calf raises, gluteal contractions, and knee raises) every 30 min. Standardized meals were consumed during each condition. Incremental areas under the curve (iAUCs) for glucose, insulin, C-peptide, and triglycerides were compared between conditions. RESULTS Compared with SIT, both activity-break conditions significantly attenuated iAUCs for glucose (SIT mean 24.2 mmol · h · Lâ1 [95% CI 20.4â28.0] vs. LW 14.8 [11.0â18.6] and SRA 14.7 [10.9â18.5]), insulin (SIT 3,293 pmol · h · Lâ1 [2,887â3,700] vs. LW 2,104 [1,696â2,511] and SRA 2,066 [1,660â2,473]), and C-peptide (SIT 15,641 pmol · h · Lâ1 [14,353â16,929] vs. LW 11,504 [10,209â12,799] and SRA 11,012 [9,723â12,301]) (all P < 0.001). The iAUC for triglycerides was significantly attenuated for SRA (P < 0.001) but not for LW (SIT 4.8 mmol · h · Lâ1 [3.6â6.0] vs. LW 4.0 [2.8â5.1] and SRA 2.9 [1.7â4.1]). CONCLUSIONS Interrupting prolonged sitting with brief bouts of LW or SRA attenuates acute postprandial glucose, insulin, C-peptide, and triglyceride responses in adults with T2D. With poor adherence to structured exercise, this approach is potentially beneficial and practical
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