A systematic collection of voltage reflection data for semi-insulating N-GaN wafer surface along with the reference reflection voltages are accomplished using a very stable continuous wave (CW) frequency stable probe source. The 2″ diameter direct-bandgap 5 µm silicon doped 10 Ω-cm GaN on 434 µm sapphire is a commercial sample and was mounted in the path of collimated BWO generated millimeter wave beam with spot size ∼3 mm and rotated 64.5° to millimeter wave reflected energy into an antenna fed zero-bias Schottky barrier diode (ZBD), a negative polarity detector with responsivity 3.
View Article and Find Full Text PDFLayered perovskites have been employed for various optoelectronic devices including solar cells and light-emitting diodes for improved stability, which need exciton transport along both the in-plane and the out-of-plane directions. However, it is not clear yet what determines the exciton transport along the in-plane direction, which is important to understand its impact toward electronic devices. Here, by employing both steady-state and transient photoluminescence mapping, it is found that in-plane exciton diffusivities in layered perovskites are sensitive to both the number of layers and organic cations.
View Article and Find Full Text PDFVoltage data acquired after probe signal transmitted through the organic film and reflected off the film surface as a function of 0.36 mW millimeter wave signal frequency in the range 110-160 GHz. Five different organic photovoltaic (OPV) materials and one 95:5 blend produced at 2 spin rates are used.
View Article and Find Full Text PDFThis article demonstrates a contactless, time-resolved, millimeter wave conductivity apparatus capable of measuring photoconductivity of a diverse range of materials. This cavity-less system determines the time-dependent magnitude of a sample's charge carrier density-mobility product by monitoring the response of a continuous, millimeter-wave probe beam following excitation of the sample by an ultrafast laser pulse. The probe beam is tunable from 110 GHz to 170 GHz and the sample response data can be obtained over the sub-nanosecond to millisecond time interval.
View Article and Find Full Text PDF3D hybrid nanostructures connecting 1D carbon nanotubes (CNTs) with 2D graphene have attracted more and more attentions due to their excellent chemical, physical and electrical properties. In this study, we firstly report a novel and facile one-step process using template-directed chemical vapor deposition (CVD) to fabricate highly nitrogen doped three-dimensional (3D) N-doped carbon nanotubes/N-doped graphene architecture (N-CNTs/N-graphene). We used nickel foam as substrate, melamine as a single source for both carbon and nitrogen, respectively.
View Article and Find Full Text PDFWe report here the synthesis of metal oxide nanosheets (MONs) directly grown on stainless steel substrates by thermal oxidation in the presence of trace amounts of water. The morphology and microstructure of MONs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM). The composition of MONs was determined by the energy dispersive system and X-ray diffraction patterns.
View Article and Find Full Text PDFIntegration of two-dimensional graphene and one-dimensional carbon nanotubes (CNTs) to create potentially useful 3D mesoscopic carbon structures with enhanced properties relative to the original materials is very desirable. Here, we report a novel and simple route using chemical vapor deposition (CVD) methods to fabricate bead-like nitrogen-doped CNT/graphene composites (NCNT/G) a simple pyrolysis of the N-rich melamine in the presence of graphene oxide (GO) as a substrate using a Mn-Ni-Co ternary catalyst. We have characterized these structures by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectra, isothermal analyses, and X-ray photoelectron spectroscopy.
View Article and Find Full Text PDFHyperpolarized C magnetic resonance spectroscopy (MRS) provides unprecedented opportunities to obtain clinical diagnostic information through in vivo monitoring of metabolic pathways. The continuing advancement of this field relies on the identification of molecular probes that can effectively interrogate pathways critical to disease. In this report, we describe the synthesis, development, and in vivo application of sodium [1-C]-glycerate ([C]-Glyc) as a novel probe for evaluating glycolysis using hyperpolarized C MRS.
View Article and Find Full Text PDFA novel approach for the synthesis of monoarylamines from aryl halides is presented. This method employs an inexpensive, nontoxic metal source (copper) and incorporates a stable ammonia surrogate (α-amino acids), obviating the need for special experimental setup or handling of ammonia reagents. This process, which is proposed to proceed via an amination-oxidation sequence, selectively promotes the transformation of a range of aryl and heteroaryl iodides as well as bromides to the corresponding monoarylamines.
View Article and Find Full Text PDFBackground: Bacillus anthracis is a pathogen that causes life-threatening disease--anthrax. B. anthracis spores are highly resistant to extreme temperatures and harsh chemicals.
View Article and Find Full Text PDFIn this study, single-walled carbon nanotubes (SWCNTs) coupled with near infrared (NIR) laser treatment to enhance SWCNT's antimicrobial activity were studied. Salmonella, agram-negative pathogenic bacteria, was used as a model bacteria in this study. We found that NIR treatment (800 nm, 475 mW, for 20 min) to bacterial suspension with 50 microg/ml SWCNTs reduced the cell growth by approximately 55.
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