Study on the optical and electrical properties of tetracyanoethylene doped bilayer graphene stack for transparent conducting electrodes

We report the optical and electrical properties of chemically-doped bilayer graphene stack by tetracyanoethylene, a strong electron acceptor. The Tetracyanoethylene doping on the bilayer graphene via charge transfer was confirmed by Raman spectroscopy and Infrared Fourier transform spectroscopy. Doped graphene shows a significant increase in the sheet carrier concentration of up to 1.520 × 1013 cm−2 with a concomitant reduction of the sheet resistance down to 414.1 Ω/sq. The high optical transmittance (ca. 84%) in the visible region in combination with the low sheet resistance of the Tetracyanoethylene-doped bilayer graphene stack opens up the possibility of making transparent conducting electrodes for practical applications

An interdisciplinary statement of scientific societies for the advancement of delirium care across Europe (EDA, EANS, EUGMS, COTEC, IPTOP/WCPT)

BACKGROUND: Delirium is a geriatric syndrome that presents in 1 out of 5 hospitalized older patients. It is also common in the community, in hospices, and in nursing homes. Delirium prevalence varies according to clinical setting, with rates of under 5% in minor elective surgery but up to 80% in intensive care unit patients. Delirium has severe adverse consequences, but despite this and its high prevalence, it remains undetected in the majority of cases. Optimal delirium care requires an interdisciplinary, multi-dimensional diagnostic and therapeutic approach involving doctors, nurses, physiotherapists, and occupational therapists. However, there are still important gaps in the knowledge and management of this syndrome. MAIN BODY: The objective of this paper is to promote the interdisciplinary approach in the prevention and management of delirium as endorsed by a delirium society (European Delirium Association, EDA), a geriatrics society (European Geriatric Medicine Society, EuGMS), a nursing society (European Academy of Nursing Science, EANS), an occupational therapy society (Council of Occupational Therapists for European Countries, COTEC), and a physiotherapy society (International Association of Physical Therapists working with Older People of the World Confederation for Physical Therapy, IPTOP/WCPT). SHORT CONCLUSION: In this paper we have strongly promoted and supported interdisciplinary collaboration underlying the necessity of increasing communication among scientific societies. We have also provided suggestions on how to fill the current gaps via improvements in undergraduate and postgraduate delirium education among European Countries.status: publishe

Non-isothermal Chemical Vapor Deposition for Increasing Carbon Nanotube Yield

Increasing the yield of single-walled carbon nanotubes (CNTs) during growth is critical to their use in widespread applications. Here, we show that we can increase the CNT yield significantly by using a simple non-isothermal, continuous cooling procedure during CNT growth. While our typical isothermal growth conditions produce sparse bundled mats, our non-isothermal growth protocol results in high-density tall forests without the need for growth promoters, additional source materials, or additional processing. In situ experiments revealed that cooling rate and temperature difference are critical and were optimized for the highest increase in CNT yield. Moreover, the general applicability of the process was demonstrated by performing chemical vapor deposition growth experiments in a tube furnace on a variety of catalyst compositions and thicknesses. The observed improvement in the non-isothermal process across all experimental platforms and catalysts occurs due to a decline in particle coarsening and to the formation of smaller particles with an order of magnitude higher density compared to isothermal growth. We 1 attribute this to the de-stabilization of the catalyst films during continuous cooling. Non- isothermal growth provides a path forward for improving SWCNT yields while retaining all other growth conditions

In Situ Mechanical Property Measurements of Amorphous Carbon-Boron Nitride Nanotube Nanostructures

To understand the mechanical properties of amorphous carbon (a-C)/boron nitride nanotube (BNNT) nanostructures, in situ mechanical tests are conducted inside a transmission electron microscope equipped with an integrated atomic force microscope system. The nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation. We demonstrate multiple in situ tensile, compressive, and lap shear tests with a-C/BNNT hybrid nanostructures. The tensile strength of the a-C/BNNT hybrid nanostructure is 5.29 GPa with about 90 vol% of a-C. The tensile strength and strain of the end-to-end joint structure with a-C welding is 0.8 GPa and 5.2% whereas the lap shear strength of the side-by-side joint structure with a-C is 0.25 GPa

Electron-beam chemistry in graphene - Effect of environmental SEM parameters on patterning and defect engineering

The engineering of defects in low-dimensional materials can enable the modulation of their optical, electrical, thermal, and structural properties. We have previously shown the ability to engineer precision patterned defects in graphene by electron beam irradiation in a controlled water vapor ambient within an environmental scanning electron microscope (ESEM). However, the relationship between instrumental parameters and structural changes in graphene are unexplored. Here, we investigate the relationships between parameters such as pressure, electron dose, and acceleration voltage on the electronic and structural properties of graphene as probed by Raman spectroscopy. There are dependencies on all of the studied parameters but electron dose is the dominant parameter that shows the most intense levels of structural modulation. Interestingly, control of instrumental parameters allows for the precision tailoring of features such as resolution (as determined by the beamskirting effect), doping, and functionalization – all of which make this process powerful for precision tuning of 2D materials and adds an enhanced technique for the development of next-generation electronics

Data system design for a hyperspectral imaging mission concept

Global ecosystem observations are important for Earth-system studies. The National Research Council's report entitled Earth Science and Applications from Space is currently guiding NASA's Earth science missions. It calls for a global land and coastal area mapping mission. The mission, scheduled to launch in the 2013-2016 timeframe, includes a hyperspectral imager and a multi-spectral thermal-infrared sensor. These instruments will enable scientists to characterize global species composition and monitor the response of ecosystems to disturbance events such as drought, flooding, and volcanic events. Due to the nature and resolution of the sensors, these two instruments produce approximately 645 GB of raw data each day, thus pushing the limits of conventional data handling and telecommunications capabilities. The implications of and solutions to the challenge of high downlink data volume were examined. Low risk and high science return were key design values. The advantages of onboard processing and advanced telecommunications methods were evaluated. This paper will present an end-to-end data handling system design that will handle the large data downlink volumes that are becoming increasingly prevalent as the complexity of Earth science increases. The designs presented here are the work of the authors and may differ from the current mission baseline.United States. National Aeronautics and Space Administratio

Polyaniline/Carbon Nanotube Sheet Nanocomposites: Fabrication and Characterization

Practical approaches are needed to take advantage of the nanometer-scale mechanical properties of carbon nanotubes (CNTs) at the macroscopic scale. This study was conducted to elucidate the salient factors that can maximize the mechanical properties of nanocomposites fabricated from commercially available CNT sheets. The CNT sheets were modified by stretching to improve CNT alignment and in situ polymerization using polyaniline (PANI), a π-conjugated conductive polymer, as a binder. The resulting CNT nanocomposites were subsequently postprocessed by hot pressing and/or high temperature treatment to carbonize the PANI as a means to improve mechanical properties. The PANI/CNT nanocomposites demonstrated significant improvement in mechanical properties compared to pristine CNT sheets. The highest specific tensile strength of PANI/stretched CNT nanocomposite was 484 MPa/(g/cm³), which was achieved in a sample with ∼42 wt % of PANI. This specimen was fabricated by in situ polymerization followed by hot pressing. The highest specific Young’s modulus of 17.1 GPa/(g/cm³) was measured on a sample that was hot-pressed and carbonized. In addition, the highest DC-electrical conductivity of 621 S/cm was obtained on a sample prepared by in situ polymerization of PANI on a stretched CNT sheet