Marvin H. Wu

North Carolina Central University

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Comparison of time-resolved millimeter-wave responses between aged and new perovskite thin films

Biswadev Roy Jingshan Chai Rui Su Franky So Marvin H. Wu

<p>This paper emerged out of analyzing simultaeously obtained microwave differential absorption profiles for perovskite thin film (methyl ammonium lead iodide) 300nm thick spun on glass substrate. The film was photoexcited using a 532 nm 0.69ns pulsewidth pulsed laser and the RF voltages obtained in the averaged signal are analyzed to point out differences in the averaged signal parameters (conductance and charge transport realted parameters) for a new and an aged perovskite sample.</p>

SIGNAL (programming language)

10.36227/techrxiv.22082360.v1

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CVD Synthesis of Graphene/Carbon Nanofiber Hybrids and “Square” Graphene Domains

Meeting abstracts/Meeting abstracts (Electrochemical Society. CD-ROM) (2013)

K. Vinodgopal Guiping Dai Marvin H. Wu

Abstract not Available.

Square (algebra)

Carbon fibers

10.1149/ma2013-02/41/2431

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Semiconductor Quantum Dot Based Nanocomposite Solar Cells

Optical science and engineering (2005)

Akira Ueda R. Mu Marvin H. Wu

Multiple exciton generation

10.1201/9781420026351.ch14

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Semi insulating N-gallium nitride (GaN) on sapphire surface reflection dataset obtained at millimeter wave frequencies 107.35–165 GHz

Data in Brief (2020)

Biswadev Roy Marvin H. Wu Branislav Vlahović

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 105 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 3.6 V/mW. Data obtained pertain to photon energies between 400 and 700 µeV (107.35-165 GHz). Data contains the 30-sample average and respective standard deviations for reference (mirror) and N-GaN reflected voltages. Anomalies in d.c. reflection coefficients (based on the raw data) are identified for users.

Extremely high frequency

Reflection

Indium gallium nitride

10.1016/j.dib.2020.106419

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Synthesis and Characterization of CdS/CdS$_{\mathrm{x}}$Se$_{\mathrm{1-x}}$ Nanowires

Bulletin of the American Physical Society (2017)

Kleyser Agueda Lopez Marvin H. Wu

Characterization

Source

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<title>Femtosecond hyper-Rayleigh scattering study of spatial orientational correlations between chromophores</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1995)

Koen Clays Marvin H. Wu André Persoons

Since the introduction of hyper-Rayleigh scattering (HRS) as a measurement technique for the first hyperpolarizability (second-order polarizability) of molecules in solution, the importance of fluctuations in the orientational distribution was realized. For isotropic solutions, a combination of the spatial and temporal fluctuations causes the instantaneous and local deviation from macroscopic centrosymmetry, which allows the observation of a second-order HRS signal. Femtosecond HRS has been used to probe the spatial orientational distribution function of nonlinear optical chromophores. The fluctuations in this function cause an HRS signal that fluctuates as a function of position. The decay of the autocorrelation function of this fluctuating signal is characterized by a correlation length. The correlation length indicates the degree of spatial correlation between the chromophores in the solid state. The development of femtosecond HRS was instrumental for the study of orientational correlations.

Hyperpolarizability

Spatial correlation

Chromophore

SIGNAL (programming language)

10.1117/12.222791

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Single-Walled Carbon Nanotubes Coupled with Near-Infrared Laser for Inactivation of Bacterial Cells

Journal of Nanoscience and Nanotechnology (2011)

Jaouad Mamouni Yongan Tang Marvin H. Wu Branislav Vlahović Liju Yang

In 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 55.5% compared with the cell sample with 50 microg/ml SWCNTs alone. Determined by the plating method, the viable cell number in the SWCNTs-NIR treated samples reduced by 2.2 log, while SWCNTs alone only had 0.7 log reduction. Imaging analysis of bacterial cells with and without NIR treatment correlated well with the growth and viable cell reduction measurement. We also found that the enhancement of SWCNTs' antimicrobial activity by NIR treatment was related to the NIR power, the NIR treatment time, and SWCNTs' concentration. The localized heating of SWCNTs under NIR treatment was the likely mechanism to enhance the antimicrobial efficiency of SWCNTs beyond its intrinsic antimicrobial activity. The results of this study suggested that SWCNTs-NIR treatment has the potential to be an effective antimicrobial method.

Bacterial growth

10.1166/jnn.2011.4163

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Citations (11)

Optical Response of Gold Nanoparticles in Dielectric Materials

MRS Proceedings (2001)

Akira Ueda Elana M. Bryant Carlton B. Maxwell C. Blake R. Mu

10.1557/proc-635-c4.40

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Melamine as a single source for fabrication of mesoscopic 3D composites of N-doped carbon nanotubes on graphene

RSC Advances (2018)

Yan Xiao-ling Hua-Fei Li Chen Wang Bang-Bang Jiang Haiyan Hu

Integration 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)

Carbon fibers

Mesoscopic physics

10.1039/c8ra01577e

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Citations (25)

Effect of 10.5 GHz CW radiofrequency radiation exposure on normal and prostate cancer cell morphology

SoutheastCon (2020)

Biswadev Roy Suryakant K. Niture Marvin H. Wu Deepak Kumar

We setup an X-band (10.525 GHz) low photon energy (0.04 meV) irradiation apparatus and exposed 4 sets of prostate cancer cells. The objectives of this project were to elucidate the effect of low radiofrequency radiation (RFR) on prostate cancer (PCa) cell metabolic activity and cell signaling. Transformed-immortalized human prostate cell line RWPE-2 cells and prostates cancer (PCa) cell lines PC3, LNCaP (Caucasian origin), or MDAPCa-2B (African American origin) were exposed for 2h with RFR (10.525 GHz), and cells were further grown for 16h at 37°C. The effect of RFR on cell morphology and the effect of RFR on prostate cancer AKT/mTOR oncogenic signaling pathways and oncogene TNFAIP8 expression was analyzed. Results suggest that no major morphological changes were observed when cells exposed with RFR. Whereas, RFR exposure increased expression of phosphorylation of serine 2448 of mammalian target of rapamycin (pS2448-mTOR) in RWPE2 and MDA-PCa2B cells and phosphorylation of serine 473 of AKT kinase (pS473-AKT) in LNCaP and PC3 cells.

10.1109/southeastcon44009.2020.9249673

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