mechanical abrasion
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Nano Energy ◽  
2021 ◽  
Vol 89 ◽  
pp. 106448
Author(s):  
Minchang Kim ◽  
Yoonsang Ra ◽  
Sumin Cho ◽  
Sunmin Jang ◽  
Dongik Kam ◽  
...  

2021 ◽  
Author(s):  
Gillibert Raymond ◽  
Alessandro Magazzù ◽  
Agnese Callegari ◽  
David Brente Ciriza ◽  
Foti Antonino ◽  
...  

Tire and Road Wear Particles (TRWP) are non-exhaust particulate matter generated by road transport means during the mechanical abrasion of tires, brakes and roads. TRWP accumulate on the roadsides and are transported into the aquatic ecosystem during stormwater runoffs. Due to their size (sub-millimetric) and rubber content (elastomers), TRWP are considered microplastics (MPs). While the amount of the MPs polluting the water ecosystem with sizes from ~ 5 μm to more than 100 μm is known, the fraction of smaller particles is unknown due to the technological gap in the detection and analysis of < 5 μm MPs. Here we show that Raman Tweezers, a combination of optical tweezers and Raman spectroscopy, can be used to trap and chemically analyze individual TWRPs in a liquid environment, down to the sub-micrometric scale. Using tire particles mechanically grinded from aged car tires in water solutions, we show that it is possible to optically trap individual sub-micron particles, in a so-called 2D trapping configuration, and acquire their Raman spectrum in few tens of seconds. The analysis is then extended to samples collected from a brake test platform, where we highlight the presence of sub-micrometric agglomerates of rubber and brake debris, thanks to the presence of additional spectral features other than carbon. Our results show the potential of Raman Tweezers in environmental pollution analysis and highlight the formation of nanosized TRWP during wear.


2021 ◽  
Vol 2021 ◽  
pp. 263-271
Author(s):  
E. Visileanu ◽  
C. Mihai ◽  
A. Ene ◽  
M.C. Grosu ◽  
R. Scarlat ◽  
...  

Nano and micro plastics (NP/MPs) represent one of the most challenging classes of micropollutants, with occurrence across all ecosystems and size distributions ranging from the nanometre to the millimetre scale. Natural environments are receiving MPs in the form of anthropogenic direct release as well as disintegrated and loose products of larger plastics via biological activities, mechanical abrasion, and UV radiation. During the processing steps, the textile yarns are subjected to friction either by different driving organs or between themselves at the binding points. The magnitude of the friction forces is influenced by the nature of the yarns, the structure of the yarn, the type, and the raw material from which the driving organs of the machines are made. The paper presents the shape and dimensions of the particle that is released in the air during the abrasion resistance test of three types of polyester yarns: spun yarn, multifilament yarn, and monofilament yarn. The structure composition of the particles consists of more microfibrils (34%.) in the case of spun yarn and the finest microparticles were obtain from monofilament yarn (0,004μm).


Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5210
Author(s):  
Brendan B. Murphy ◽  
Brittany H. Scheid ◽  
Quincy Hendricks ◽  
Nicholas V. Apollo ◽  
Brian Litt ◽  
...  

A low and stable impedance at the skin–electrode interface is key to high-fidelity acquisition of biosignals, both acutely and in the long term. However, recording quality is highly variable due to the complex nature of human skin. Here, we present an experimental and modeling framework to investigate the interfacial impedance behavior, and describe how skin interventions affect its stability over time. To illustrate this approach, we report experimental measurements on the skin–electrode impedance using pre-gelled, clinical-grade electrodes in healthy human subjects recorded over 24 h following four skin treatments: (i) mechanical abrasion, (ii) chemical exfoliation, (iii) microporation, and (iv) no treatment. In the immediate post-treatment period, mechanical abrasion yields the lowest initial impedance, whereas the other treatments provide modest improvement compared to untreated skin. After 24 h, however, the impedance becomes more uniform across all groups (<20 kΩ at 10 Hz). The impedance data are fitted with an equivalent circuit model of the complete skin–electrode interface, clearly identifying skin-level versus electrode-level contributions to the overall impedance. Using this model, we systematically investigate how time and treatment affect the impedance response, and show that removal of the superficial epidermal layers is essential to achieving a low, long-term stable interface impedance.


2021 ◽  
Vol 12 ◽  
Author(s):  
Kathleen L. Vincent ◽  
Patrice A. Frost ◽  
Massoud Motamedi ◽  
Edward J. Dick ◽  
Jingna Wei ◽  
...  

Vaginal mucosal surfaces naturally offer some protection against sexually transmitted infections (STIs) including Human Immunodeficiency Virus-1, however topical preventative medications or vaccine designed to boost local immune responses can further enhance this protection. We previously developed a novel mucosal vaccine strategy using viral vectors integrated into mouse dermal epithelium to induce virus-specific humoral and cellular immune responses at the site of exposure. Since vaccine integration occurs at the site of cell replication (basal layer 100-400 micrometers below the surface), temporal epithelial thinning during vaccine application, confirmed with high resolution imaging, is desirable. In this study, strategies for vaginal mucosal thinning were evaluated noninvasively using optical coherence tomography (OCT) to map reproductive tract epithelial thickness (ET) in macaques to optimize basal layer access in preparation for future effective intravaginal mucosal vaccination studies. Twelve adolescent female rhesus macaques (5-7kg) were randomly assigned to interventions to induce vaginal mucosal thinning, including cytobrush mechanical abrasion, the chemical surfactant spermicide nonoxynol-9 (N9), the hormonal contraceptive depomedroxyprogesterone acetate (DMPA), or no intervention. Macaques were evaluated at baseline and after interventions using colposcopy, vaginal biopsies, and OCT imaging, which allowed for real-time in vivo visualization and measurement of ET of the mid-vagina, fornices, and cervix. P value ≤0.05 was considered significant. Colposcopy findings included pink, rugated tissue with variable degrees of white-tipped, thickened epithelium. Baseline ET of the fornices was thinner than the cervix and vagina (p&lt;0.05), and mensing macaques had thinner ET at all sites (p&lt;0.001). ET was decreased 1 month after DMPA (p&lt;0.05) in all sites, immediately after mechanical abrasion (p&lt;0.05) in the fornix and cervix, and after two doses of 4% N9 (1.25ml) applied over 14 hrs in the fornix only (p&lt;0.001). Histological assessment of biopsied samples confirmed OCT findings. In summary, OCT imaging allowed for real time assessment of macaque vaginal ET. While varying degrees of thinning were observed after the interventions, limitations with each were noted. ET decreased naturally during menses, which may provide an ideal opportunity for accessing the targeted vaginal mucosal basal layers to achieve the optimum epithelial thickness for intravaginal mucosal vaccination.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Seyed Mehran Mirmohammadi ◽  
Sasha Hoshian ◽  
Ville P. Jokinen ◽  
Sami Franssila

AbstractA polydimethylsiloxane (PDMS)/Cu superhydrophobic composite material is fabricated by wet etching, electroless plating, and polymer casting. The surface topography of the material emerges from hierarchical micro/nanoscale structures of etched aluminum, which are rigorously copied by plated copper. The resulting material is superhydrophobic (contact angle > 170°, sliding angle < 7° with 7 µL droplets), electrically conductive, elastic and wear resistant. The mechanical durability of both the superhydrophobicity and the metallic conductivity are the key advantages of this material. The material is robust against mechanical abrasion (1000 cycles): the contact angles were only marginally lowered, the sliding angles remained below 10°, and the material retained its superhydrophobicity. The resistivity varied from 0.7 × 10–5 Ωm (virgin) to 5 × 10–5 Ωm (1000 abrasion cycles) and 30 × 10–5 Ωm (3000 abrasion cycles). The material also underwent 10,000 cycles of stretching and bending, which led to only minor changes in superhydrophobicity and the resistivity remained below 90 × 10–5 Ωm.


CIRP Annals ◽  
2021 ◽  
Author(s):  
Hyun Jun Ryu ◽  
Dong Geun Kim ◽  
Sukkyung Kang ◽  
Ji-hun Jeong ◽  
Sanha Kim

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