scholarly journals Controllable Preparation of Fe3O4@RF and Its Evolution to Yolk–Shell-Structured Fe@C Composite Microspheres with High Microwave Absorbing Performance

Coatings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 62
Author(s):  
Xue Li ◽  
Peng Lou ◽  
Longquan Yang
Keyword(s):  
Magnetic Loss ◽  
Vital Role ◽  
Carbonization Temperature ◽  
Polymer Shell ◽  
Composite Microspheres ◽  
Before And After ◽  
One Step ◽  
Microwave Absorbing ◽  
Temperature Time ◽  
Controllable Preparation

Fe3O4@RF microspheres with different phenolic (RF) layer thicknesses are prepared by adjusting the polymerization time. With the prepared Fe3O4@RF as the precursor, Fe@C composite microspheres with rattle-like morphology are obtained through one-step controlled carbonization. This method simplifies the preparation of rattle-shaped microspheres from sandwich microspheres. Fe@C microspheres exhibit excellent microwave absorbing properties. The morphology and composition of the product are investigated depending on the effects of carbonization temperature, time and thickness of the RF layer. When the carbonization temperature is 700 °C, the carbonization time is 12 h and the polymer shell thickness is 62 nm, the inner hollow Fe3O4 is completely reduced to Fe. The absorption properties of the materials are compared before and after the reduction of Fe3O4. Both Fe@C-12 and Fe3O4@C-700 show excellent absorbing properties. When the filler content is 50%, the maximum reflection loss (RLmax) of the rattle-shaped Fe@C microspheres is −50.15 dB, and the corresponding matching thickness is 3.5 mm. At a thickness of 1.7 mm, the RLmax of Fe3O4@C-700 is −44.42 dB, which is slightly worse than that of Fe@C-12. Both dielectric loss and magnetic loss play a vital role in electromagnetic wave absorption. This work prepares rattle-shaped absorbing materials in a simple way, which has significance for guiding the construction of rattle-shaped materials.

scholarly journals Single Step 2-Port Device De-Embedding Algorithm for Fixture-DUT-Fixture Network Assembly

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1275
Author(s):  
Simone Scafati ◽  
Enza Pellegrino ◽  
Francesco de Paulis ◽  
Carlo Olivieri ◽  
James Drewniak ◽  
...  
Keyword(s):  
Standard Technique ◽  
Single Step ◽  
Scattering Parameters ◽  
Linear Set ◽  
S Parameter ◽  
Parameter Conversion ◽  
Before And After ◽  
One Step ◽  
Typical Measurement

The de-embedding of measurement fixtures is relevant for an accurate experimental characterization of radio frequency and digital electronic devices. The standard technique consists in removing the effects of the measurement fixtures by the calculation of the transfer scattering parameters (T-parameters) from the available measured (or simulated) global scattering parameters (S-parameters). The standard de-embedding is achieved by a multiple steps process, involving the S-to-T and subsequent T-to-S parameter conversion. In a typical measurement setup, two fixtures are usually placed before and after the device under test (DUT) allowing the connection of the device to the calibrated vector network analyzer coaxial ports. An alternative method is proposed in this paper: it is based on the newly developed multi-network cascading algorithm. The matrices involved in the fixture-DUT-fixture cascading gives rise to a non-linear set of equations that is in one step analytically solved in closed form, obtaining a unique solution. The method is shown to be effective and at least as accurate as the standard multi-step de-embedding one.

scholarly journals Caregiver Burden: Caregiving Workshops Have a Positive Impact on Those Caring for Individuals With Dementia in Arkansas

2021 ◽  
Vol 8 ◽  
pp. 237437352110180
Author(s):  
Robin E. McAtee ◽  
Laura Spradley ◽  
Leah Tobey ◽  
Whitney Thomasson ◽  
Gohar Azhar ◽  
...  
Keyword(s):  
Caregiver Burden ◽  
Health Care Providers ◽  
Positive Impact ◽  
Educational Programs ◽  
Vital Role ◽  
Complex Care ◽  
Care Providers ◽  
Dementia Caregivers ◽  
Before And After ◽  
Burden Scale

Millions of Americans live with dementia. Caregivers of this population provide countless hours of multifaceted, complex care that frequently cause unrelenting stress which can result in immense burden. However, it is not fully understood what efforts can be made to reduce the stress among caregivers of persons with dementia (PWD). Therefore, the aim of this pretest–posttest designed study was to evaluate changes in caregiver burden after providing an educational intervention to those caring for PWD in Arkansas. Forty-one participants completed the Zarit Caregiver Burden Scale before and after attending a 4-hour dementia-focused caregiving workshop. The analysis of the means, standard deviations, and paired t tests showed that there was an increase in the confidence and competence in caring for PWD 30 to 45 days after attending the workshop. Health care providers need to understand both the vital role caregivers provide in managing a PWD and the importance of the caregiver receiving education about their role as a caregiver. Utilizing caregiver educational programs is a first step.

Development of two dosimetry systems based on basic violet dye for possible use as radiation dosimeters

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nehad Magdy ◽  
Sameh Gafar
Keyword(s):  
Gamma Ray ◽  
Raw Materials ◽  
Absorbed Dose ◽  
Chemical Yield ◽  
Radiation Sensitivity ◽  
Vital Role ◽  
Radiation Chemical ◽  
Content Type ◽  
Before And After

Purpose The purpose of this research paper is to study a comparison between two dosimetry systems, both of them based on basic violet dye (BV). Design/methodology/approach The first system depends on (BV) (incorporating polyvinyl alcohol) as a thin-film dosimeter. The second system also relies on (BV) as a solution dosimeter, which is more sensitive to gamma rays. The two prepared film/solutions have a considerable signal that decreases upon irradiation and the strength of the signal decreases with increasing radiation dose. Findings The gamma ray absorbed dose for these dosimeters was found to be up to 35 kGy for films and 1 kGy for the liquid phase. All dosimetric characteristics as radiation chemical yield, additive substance, dose-response function, radiation sensitivity, also before and after-irradiation stability under various conditions were considered. Practical implications It is expected the vital role of gamma radiation on this dye in its two forms or two media. This reveals their wide applications in the field of gamma irradiation processing. Originality/value These two dosimetry systems which depend upon the same dye are safe to handle, inexpensive, available raw materials and can be applied in various dosimetry applications as mentioned above.

Durability of Lubricated Icephobic Coatings under Multiple Icing/Deicing Cycles

2021 ◽  
Author(s):  
Valentina Donadei ◽  
Heli Koivuluoto ◽  
Essi Sarlin ◽  
Petri Vuoristo
Keyword(s):  
Industrial Applications ◽  
Power Lines ◽  
Operational Performance ◽  
Flame Spraying ◽  
Mechanical Interlocking ◽  
Properties Of Coatings ◽  
Before And After ◽  
Outdoor Environments ◽  
One Step ◽  
Ice Adhesion

Abstract In subzero conditions, atmospheric ice naturally accretes on surfaces in outdoor environments. This accretion can compromise the operational performance of several industrial applications, such as wind turbines, power lines, aviation, and maritime transport. To effectively prevent icing problems, the development of durable icephobic coating solutions is strongly needed. Here, the durability of lubricated icephobic coatings was studied under repeated icing/deicing cycles. Lubricated coatings were produced in one-step by flame spraying with hybrid feedstock injection. The coating icephobicity was investigated by accreting ice from supercooled microdroplets using an icing wind tunnel. The ice adhesion strength was evaluated by a centrifugal ice adhesion tester. The icing performance was investigated over four icing/deicing cycles. Surface properties of coatings, such as morphology, topography, chemical composition and wettability, were analyzed before and after the cycles. The results showed an increase in ice adhesion over the cycles, while a stable icephobic behaviour was retained for one selected coating. Moreover, consecutive ice detachment caused a surface roughness increase. This promotes the formation of mechanical interlocking with ice, thus justifying the increased ice adhesion. Finally, the coating hydrophobicity mainly decreased as a consequence of the damaged surface topography. In summary, lubricated coatings retained a good icephobic level after the cycles, thus demonstrating their potential for icephobic applications.

One-step synthesis of PI@Fe3O4 composite microspheres and practical applications in Cu(ii) ion adsorption

RSC Advances ◽  
2015 ◽  
Vol 5 (108) ◽  
pp. 88943-88949 ◽  
Author(s):  
Chunyan Qu ◽  
Changwei Liu ◽  
Haoran Zhou ◽  
Weimiao Yu ◽  
Dezhi Wang ◽  
...  
Keyword(s):  
Ion Adsorption ◽  
Thermal Stabilities ◽  
Practical Applications ◽  
Composite Microspheres ◽  
One Step

We proposed a mechanism for the synthesis of PI/Fe3O4 composite microspheres from PAAS and iron(iii); and the composite microspheres have excellent thermal stabilities.

scholarly journals Role of nitric oxide-containing factors in the ventilatory and cardiovascular responses elicited by hypoxic challenge in isoflurane-anesthetized rats

2014 ◽  
Vol 116 (11) ◽  
pp. 1371-1381 ◽  
Author(s):  
James P. Mendoza ◽  
Rachael J. Passafaro ◽  
Santhosh M. Baby ◽  
Alex P. Young ◽  
James N. Bates ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Heart Rate ◽  
Cardiovascular Responses ◽  
Vital Role ◽  
Initial Increase ◽  
Ventilatory Responses ◽  
Arterial Blood ◽  
Anesthetized Rats ◽  
Before And After

Exposure to hypoxia elicits changes in mean arterial blood pressure (MAP), heart rate, and frequency of breathing (fr). The objective of this study was to determine the role of nitric oxide (NO) in the cardiovascular and ventilatory responses elicited by brief exposures to hypoxia in isoflurane-anesthetized rats. The rats were instrumented to record MAP, heart rate, and fr and then exposed to 90 s episodes of hypoxia (10% O2, 90% N2) before and after injection of vehicle, the NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME), or the inactive enantiomer d-NAME (both at 50 μmol/kg iv). Each episode of hypoxia elicited a decrease in MAP, bidirectional changes in heart rate (initial increase and then a decrease), and an increase in fr. These responses were similar before and after injection of vehicle or d-NAME. In contrast, the hypoxia-induced decreases in MAP were attenuated after administration of l-NAME. The initial increases in heart rate during hypoxia were amplified whereas the subsequent decreases in heart rate were attenuated in l-NAME-treated rats. Finally, the hypoxia-induced increases in fr were virtually identical before and after administration of l-NAME. These findings suggest that NO factors play a vital role in the expression of the cardiovascular but not the ventilatory responses elicited by brief episodes of hypoxia in isoflurane-anesthetized rats. Based on existing evidence that NO factors play a vital role in carotid body and central responses to hypoxia in conscious rats, our findings raise the novel possibility that isoflurane blunts this NO-dependent signaling.

Assessment by Audiences Shows Little Effect of Science Communication Training

2020 ◽  
pp. 107554702097163
Author(s):  
Margaret A. Rubega ◽  
Kevin R. Burgio ◽  
A. Andrew M. MacDonald ◽  
Anne Oeldorf-Hirsch ◽  
Robert S. Capers ◽  
...  
Keyword(s):  
Science Communication ◽  
Vital Role ◽  
Communication Training ◽  
Communication Course ◽  
Good Communication ◽  
Public Science ◽  
The Public ◽  
Before And After ◽  
Science Community

As the science community has recognized the vital role of communicating to the public, science communication training has proliferated. The development of rigorous, comparable approaches to assessment of training has not kept pace. We conducted a fully controlled experiment using a semester-long science communication course, and audience assessment of communicator performance. Evaluators scored the communication competence of trainees and their matched, untrained controls, before and after training. Bayesian analysis of the data showed very small gains in communication skills of trainees, and no difference from untrained controls. High variance in scores suggests little agreement on what constitutes “good” communication.

Mixed Polymers and Vulcanizable Plasticizers. Relation to the Vulcanization of Rubber

1941 ◽  
Vol 14 (4) ◽  
pp. 826-834
Author(s):  
B. S. Garvey ◽  
C. H. Alexander ◽  
F. E. Küng ◽  
D. E. Henderson
Keyword(s):  
Physical Properties ◽  
Vital Role ◽  
Mixed Composition ◽  
Manufacturing Operations ◽  
Vulcanized Rubber ◽  
Hydrocarbon Solvents ◽  
Original Shape ◽  
Before And After ◽  
The Difference

Abstract The vital role played by rubber in modern civilization is due in part to the physical properties displayed by soft vulcanized rubber in service and in part to the characteristics of unvulcanized milled rubber which make it amenable to manufacturing operations. Vulcanization of rubber is a change in condition usually induced by heating it with sulfur, and is best defined by contrasting the difference in physical properties: To illustrate, compare a mill-mixed composition before and after vulcanization. Before vulcanization it is easily pulled apart and, if considerably extended, shows little tendency to retract, although, under impact, the recovery or rebound is considerable. If heated it becomes even softer and more plastic, and can easily be formed into any desired shape. If cooled to 0° C or somewhat lower, it becomes stiff and boardy. It is readily soluble in hydrocarbon solvents. When two fresh surfaces are pressed together, they coalesce and become practically integral. This tack, as it is called, is valuable in manufacturing operations. After vulcanization, rubber is tough and strong and, after even a slow distortion, returns rapidly to its original shape. It has little tendency to flow and is devoid of tack. It swells but does not dissolve in hydrocarbon solvents. These characteristics change very little from −40° to well above 100° C.

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