Investigation of Dropwise Condensation on a Super-Aligned Carbon Nanotube Mesh-Coated Surface.

Enhanced vapor condensation is a critical issue for improving the efficiency of energy conversion, thermal management, water recovery, and treatment. Low-energy surfaces incorporating micro/nanoscale roughness have been reported to significantly promote vapor condensation. In this research, the mesh structures of super-aligned carbon nanotube (SACNT) films were prepared by crossing monolayer SACNT films on a copper substrate. Then, the sustaining dropwise condensation was achieved on the SACNT mesh-coated surface. The SACNT mesh-coated surface could obviously enhance the coalescence and sweeping departure of the condensing droplets. Additionally, the measured overall heat transfer coefficient (HTC) of the SACNT mesh-coated surface demonstrated a 36% enhancement compared to that on the bare copper surface. The parallel stacking of SACNT films with different groove structures was also studied, and a 15% enhancement in the HTC was shown as compared with the bare copper surface. Furthermore, we developed a morphology-based model to theoretically analyze the condensation-enhancement mechanism on a SACNT mesh-coated surface. The SACNT surfaces also have advantages of low cost, durability, flexibility, and extensibility. Our findings revealed that the SACNT films could be readily used as vapor condensation-strengthening surfaces, further extending their potential applications to industrial equipment.

How Does Nature Evade the "Larger is Weaker" Fate of Ultralong Silk ß-Sheet Nanocrystallites.

Silk protein builds up one of the strongest fibers superior to most synthetic and natural polymers. However, the strengthening mechanisms of the silk proteins remain largely elusive because of their complex nanocomposite structures. Here, we report an unusual behavior of this kind of material that is distinctively different from those of metals and other polymers. We find that there are multiple interface microcracks nucleating and stacking under the shear loading, dividing the interchain interface into small segments, by which the silk protein can achieve a high strength even with the ultralong chains. This is a new strategy of microstructure design of soft matter that could avoid the "larger is weaker" fate due to the increase of the chain length. This novel mechanism is crucial for building strong polymer materials with long chain molecules and at the same time retaining their complex functional and structural properties.

The impact of auditory nerve functional states on the correlations between human and computer decisions for electrically evoked compound action potential threshold.

OBJECTIVES: The electrically evoked compound action potential (ECAP) is widely used in clinical to reflect the functional states of the auditory nerve in cochlear implant (CI) recipients, especially in pediatric CI users. Currently, the software can automatically provide the ECAP threshold, which is convenient and not affected by the subjective judgement of the clinicians. However, it remains unclear whether the correlations between human and computer decisions for ECAP threshold can be affected by auditory nerve functional states, which is also the main purpose of our present study. METHODS: Intracochlear electrical stimulation, which can decrease the excitability of the auditory nerve, was used to change the auditory nerve functional states of guinea pigs. Ten normal-hearing guinea pigs were implanted with CIs unilaterally. ECAPs were recorded both before and after the electrical stimulation, representing different functional states of the auditory nerve. Forward masking (FwdMsk) and alternating polarity (AltPol), two most commonly-used artifact-reduction methods, were applied to the measurements. All measurements recorded by the software were saved for computer and human analysis with linear regression and visual detection methods. RESULTS: The correlations between human and computer performance in the peak-picking process were not affected by auditory nerve states and artifact-reduction methods. However, complicated findings were observed for ECAP threshold. With FwdMsk utilized, weaker correlations between human and computer performance were observed in abnormal state compared to those in normal state. Regardless of the functional states of the auditory nerve, the results revealed stronger correlations in AltPol than those in FwdMsk. Furthermore, when compared with human decision, computer linear-regression threshold (C-LRT) was always less accurate than computer visual-detection threshold (C-VDT), which was not affected by auditory nerve states. CONCLUSIONS: (1) the functional states of the auditory nerve can definitely affect the correlations between human and computer decisions for ECAP threshold, but the impact is limited to the FwdMsk method; (2) AltPol can produce stronger correlations compared with FwdMsk, which is not affected by auditory nerve states; and (3) regardless of the auditory nerve states, C-VDT can always show higher consistency with human decision, while C-LRT reveals more variability.

Electrical Stimulation Degenerated Cochlear Synapses Through Oxidative Stress in Neonatal Cochlear Explants.

Neurostimulation devices use electrical stimulation (ES) to substitute, supplement or modulate neural function. However, the impact of ES on their modulating structures is largely unknown. For example, recipients of cochlear implants using electroacoustic stimulation experienced delayed loss of residual hearing over time after ES, even though ES had no impact on the morphology of hair cells. In this study, using a novel model of cochlear explant culture with charge-balanced biphasic ES, we found that ES did not change the quantity and morphology of hair cells but decreased the number of inner hair cell (IHC) synapses and the density of spiral ganglion neuron (SGN) peripheral fibers. Inhibiting calcium influx with voltage-dependent calcium channel (VDCC) blockers attenuated the loss of SGN peripheral fibers and IHC synapses induced by ES. ES increased ROS/RNS in cochlear explants, but the inhibition of calcium influx abolished this effect. Glutathione peroxidase 1 (GPx1) and GPx2 in cochlear explants decreased under ES and ebselen abolished this effect and attenuated the loss of SGN peripheral fibers. This finding demonstrated that ES induced the degeneration of SGN peripheral fibers and IHC synapses in a current intensity- and duration-dependent manner in vitro. Calcium influx resulting in oxidative stress played an important role in this process. Additionally, ebselen might be a potential protector of ES-induced cochlear synaptic degeneration.

Icephobic behaviors of superhydrophobic amorphous carbon nano-films synthesized from a flame process.

HYPOTHESIS: Ice formation and accumulation are critical issues for the breakdown of power lines, aircraft wings, and other important facilities in cold environments. Although a large number of passive icephobic surfaces based on superhydrophobic materials have been designed in the last few decades, the complicated and high-cost fabrication processes limit them beyond large-scale applications. Therefore it is indeed to further investigate the readily available and low-cost functional icephobic materials. EXPERIMENTS: In this article, a kind of superhydrophobic film consisting of amorphous carbon nano-particles was synthesized on common glass by the ethanol-flame synthesis method. More importantly, the microstructures of the as-prepared carbon nano-film, as well as the static contact angles, and the dynamic sliding-off angles of water droplets, were fully measured. The icephobic properties of the carbon nano-film and bare glass were also carefully investigated by measuring the critical parameters, including freezing times of water droplets, ice adhesion strengths, and dynamic sliding-off angles of droplets at different cooling temperatures. FINDINGS: Results of static contact angle and dynamic sliding-off angle measurements reveal that the as-synthesized carbon nano-film has outstanding superhydrophobic properties. Furthermore, water droplets could completely roll off from the carbon nano-film with inclination angles >5° at cooling temperatures as low as -23 °C. It is also observed that the superhydrophobic carbon nano-film remarkably decelerate the freezing process of water droplets on common glass. In addition, the ice adhesion strength is remarkably reduced by the carbon nano-film. Hence, the carbon nano-film yields excellent icephobic properties by effectively reducing the formation and accumulation of ice. Thus, our work provides a potential approach for low-cost icephobic applications.

[Development of electrically evoked auditory brainstem response modules of REZ-I domestic cochlear implant device].

OBJECTIVE: To develop electrically evoked auditory brainstem response(EABR) modules of REZ-I domestic cochlear implant device, and testify the reliability and validity of the modules. METHODS: Postoperative EABR were recorded in guinea pigs by using the self-designed EABR module. RESULTS: EABR waves were recorded in all 15 ears of 9 guinea pigs with normal hearing. The threshold was (159.00 ± 50.21) current level (CL) and eIII wave latency was (2.36 ± 0.46) ms of 100 µs pulse width stimulation; for 150 µs pulse width stimulation, the threshold was (131.44 ± 49.25) CL and eIII wave latency was (2.59 ± 0.46)ms; for 200 µs pulse width stimulation, the threshold was (119.63 ± 52.56) CL and e III wave latency was (2.62 ± 0.44)ms. CONCLUSION: According the preliminary results of the study, the reliability and stability of the EABR modules of domestic cochlear implant device can meet the demands of EABR recording.