4 research outputs found
Self-detecting gate-tunable nanotube paddle resonators
No full textWe have fabricated suspended metal paddle resonators with carbon nanotubes functioning as self-detecting torsional springs. We observe gate-tunable resonances that either tune to higher or to lower frequencies when increasing the dc voltage on the back gate. We attribute the former modes to flexural vibrations of the paddle resonator, while the latter ones are identified as torsional vibrations. Compared to top-down silicon fabricated paddle resonators, nanotube springs have smaller torsional spring constants and provide a larger frequency tunability.Kavli Institute of NanoscienceApplied Science
Towards CMOS-compatible single-walled carbon nanotube resonators
No full textAbstract: We report a totally CMOS-compatible fabrication technique to assemble horizontally suspended single-walled carbon nanotube (SWCNT) resonators. Individual SWCNTs are assembled in parallel at multiple sites by a technique called dielectrophoresis. The mechanical resonance frequencies of the suspended SWCNTs are in the range of 2035 MHz as determined from the piezoresistive response of the resonators during electrostatic actuation. The resistance of the suspended SWCNT either remains unchanged or increases or decreases significantly as a function of the actuation frequency. This can be explained by the effect the nanotube chirality has on the piezoresistive gauge factor
Postprandial Cardiometabolic Parameters in Older Adults with Normal-Weight Obesity: A Cross-Sectional Pilot Study
No full textBackground/Objectives: Normal-weight obesity describes those with a normal body mass index (BMI) and high body fat percent. Older adults with normal-weight obesity (NWO-O) are at increased risk for cardiovascular disease (CVD), but underlying mechanisms remain unclear. This pilot study examined whether NWO-O had an unfavorable cardiometabolic response to acute high-fat meal intake compared to normal BMI, low body fat percent individuals that were both older (NWL-O) and younger (NWL-Y). Methods: Participants (N = 29) with a normal BMI were grouped as follows: NWL-Y (18–35 years, low body fat percent; n = 12), NWL-O (≥60 years, low body fat percent; n = 9), and NWO-O (≥60 years, high body fat percent; n = 8). All participants completed an abbreviated fat tolerance test (75 g fat). Fasting and 4 h blood samples were collected to measure lipids (triglycerides and high-density lipoprotein cholesterol [HDL-C]), biomarkers of intestinal permeability (lipopolysaccharide binding protein [LBP] and soluble cluster of differentiation [sCD14]), and the inflammatory marker interleukin (IL)-6. Results: NWO-O had higher percent, absolute, and trunk fat compared to NWL-Y and NWL-O (p’s ≤ 0.01). Conversely, percent lean mass was lower in NWO-O versus both NWL groups (p’s ≤ 0.01). NWO-O had higher fasting triglycerides than NWL-Y (p p p p = 0.06). Fasting IL-6 was higher in NWO-O relative to NWL-Y (p p’s < 0.01). Conclusions: NWO-O had an exaggerated postprandial triglyceride response compared to younger and similar-aged NWL individuals, which could reflect hepatic very low-density lipoprotein overproduction or impaired triglyceride clearance. Future work should continue to investigate the role of postprandial dyslipidemia in NWO-O’s reported CVD risk
Graphene nanoplatelets in epoxy system: dispersion, reaggregation, and mechanical properties of nanocomposites
No full textThe use of graphene nanocomposites in advanced applications has attracted much attention in recent years. However, in order to substitute traditional epoxy reinforcements with graphene, there are still some issues like dispersion, homogenization, and reaggregation. In this paper, graphene bundles dispersed in two-component epoxy system by bath sonication, dispersion state, and reaggregation behavior of graphene in this system have been studied. Light transmittance in ultraviolet-visible spectroscopy has been used to quantify the reaggregation by a series of controlled experiments. After 18 mins sonication of 0.005 wt% graphene dispersion at 20°C, the light transmittance decreased from 68.92% to 54.88% in liquid epoxy and decreased from 72.80% to 46.42% in hardener; while increasing the temperature from 20°C to 60°C, the light transmittance in liquid epoxy decreased from 65.96% to 53.21% after 6 mins sonication. With the incorporation of 0.3 wt% graphene, the tensile strength of nanocomposites increased from 57.2 MPa to 64.4 MPa and the storage modulus increased from 1.66 GPa to 2.16 GPa. The results showed that the dispersion state depends on the function of sonication time and temperature, and graphene has a significant reinforcement effect on epoxy
