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We demonstrate a new, facile gas-phase electrostatic approach to successfully quantify equivalent surface area of graphene oxide (GO) colloid on a number basis. Mobility diameter (dp,m)-based distribution and the corresponding equivalent surface area (SA) of GO colloids (i.e., with different lateral aspect ratios) were able to be identified by electrospray-differential mobility analysis (ES-DMA) coupled to a condensation particle counter (CPC) and an aerosol surface area analyzer (ASAA). A correlation of SA ∝ dp,m2.0 was established using the ES-DMA-CPC/ASAA, which is consistent with the observation by the 2-dimensional image analysis of size-selected GOs. An ultrafast surface area measurement of GO colloid was achieved via a direct coupling of ES with a combination of ASAA and CPC (i.e., measurement time was 2 min per sample; without size classification). The measured equivalent surface area of GO was ∼202 ± 7 m2 g–1, which is comparable to Brunauer–Emmett–Teller (BET) surface area, ∼240 ± 59 m2 g–1. The...

A systematic study to reveal the relationship between the surface oxygen-containing functionalities of sub-10-nm GNRs and their electrochemical properties for lithium-ion batteries has been presented. Sub-10-nm GNRs with controlled oxygen-containing groups were synthesized by a green and scalable intercalation-assisted unzipping SWCNTs. Detailed materials characterizations including TEM, XRD, Raman and XPS indicate that KNO 3 could be an effective intercalation agent to facilitate the SWCNT unzipping by reducing the strong Van der Waals force attraction of bundled SWCNT. The levels of surface functionalities of sub-10-nm GNR were tuned by carefully controlling the KMnO 4 concentration during the unzipping process. The electrochemical analysis suggests that the as-produced sub-10-nm GNR with 31.4 atomic percent (atom %) oxygen-containing functional groups showed the highest capacity of 490.4 mAh g −1 after 100 cycles. This work proposed that sub-10-nm GNRs with appropriate oxygen-functional groups can be a promising electrode material for high performance lithium-ion batteries.

Toxicity issues and biocompatibility concerns with traditional classical chemical cross-linking processes prevent them from being universal approaches for hydrogel fabrication for tissue engineering. Physical cross-linking methods are non-toxic and widely used to obtain cross-linked polymers in a tunable manner. Therefore, in the current study, argon micro-plasma was introduced as a neutral energy source for cross-linking in fabrication of the desired gelatin-graphene oxide (gel-GO) nanocomposite hydrogel scaffolds. Argon microplasma was used to treat purified gelatin (8% w/v) containing 0.1∼1 wt% of high-functionality nano-graphene oxide (GO). Optimized plasma conditions (2,500 V and 8.7 mA) for 15 min with a gas flow rate of 100 standard cm3/min was found to be most suitable for producing the gel-GO nanocomposite hydrogels. The developed hydrogel was characterized by the degree of cross-linking, FTIR spectroscopy, SEM, confocal microscopy, swelling behavior, contact angle measurement, and rheology. The cell viability was examined by an MTT assay and a live/dead assay. The pore size of the hydrogel was found to be 287 ± 27 µm with a contact angle of 78° ± 3.7°. Rheological data revealed improved storage as well as a loss modulus of up to 50% with tunable viscoelasticity, gel strength, and mechanical properties at 37 °C temperature in the microplasma-treated groups. The swelling behavior demonstrated a better water-holding capacity of the gel-GO hydrogels for cell growth and proliferation. Results of the MTT assay, microscopy, and live/dead assay exhibited better cell viability at 1% (w/w) of high-functionality GO in gelatin. The highlight of the present study is the first successful attempt of microplasma-assisted gelatin-GO nano composite hydrogel fabrication that offers great promise and optimism for further biomedical tissue engineering applications.

We have demonstrated an effective intercalation of multi-walled carbon nanotubes (MWCNTs) for the green and scalable synthesis of graphene nanoribbons (GNRs) using an intercalation-assisted longitudinal unzipping of MWCNTs. The key step is to introduce an intercalation treatment of raw MWCNTs with KNO3 and H2SO4, making it promising to decrease the strong van der Waals attractions in the MWCNTs bundles and between the coaxial graphene walls of CNTs. Systematic micro Raman, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations suggest that potassium, nitrate and sulfate ions play an important role in the CNT intertube and intratube intercalations during the pretreatment. Detailed scanning electron microscopy (SEM), transmission electron microscopy, XRD and micro Raman characterizations indicate that the developed methodology possesses the ability to synthesis GNRs effectively with an improved CNT concentration in H2SO4 of 10 mg/ml at 70 °C, which is amenable to industrial-scale production because of the decreased amount of strong acid. Our work provides a scientific understanding how to enhance the GNR formation by accelerating the CNT longitudinal unzipping via suitable molecular intercalation.

In this paper, a wireless sensor module (WSM) and network used for cool box temperature monitoring in cold chain logistics is presented. The proposed WSM is implemented by integrating mainly a wireless microcontroller JENNIC 5418 based on IEEE 802.15.4 standard with a thermocouple sensing converter MAX31855. The transmitter power and sensitivity of the proposed module are 2.5 dBm and −95 dBm respectively, and the temperature range/resolution of the sensing converter is −40∼125 °C/0.25 °C. In order to demonstrate the communication quality of the proposed WSM, the point-to-point link quality indication (LQI) has been measured in a 20-foot cargo container filled up with the watered Styrofoam boxes. Furthermore, cool box temperature monitoring and cargo container position tracking regularly at remote-end are demanded for preventing the food from perishing under transportation in cold-chain logistics. Therefore, the access point (coordinator) of the wireless sensor network integrated with the GPS and 3G communication system is considerable, and it has been developed in our project.

The iLamp system is a sensor-enhanced desk lamp with surface-tracking capability based on received light intensity. It consists of two components: lamp and bookmark. The bookmark is a ZigBee-enabled sensor node that can report its sensed light intensity to the lamp with a user-friendly interface and two-way communication capability. The lamp can use its LEDs to locate user's reading surface to which the bookmark is attached, move toward the surface, and further tune its luminous intensity to meet user's preference. We develop the geometrical model for surface tracking. iLamp demonstrates a new centimeter-level location-tracking system using light intensity alone without other extra media or devices.