Joseph S. Melinger

Bio: Joseph S. Melinger is an academic researcher from United States Naval Research Laboratory. The author has contributed to research in topics: Terahertz spectroscopy and technology & Förster resonance energy transfer. The author has an hindex of 43, co-authored 189 publications receiving 6494 citations. Previous affiliations of Joseph S. Melinger include Georgia Institute of Technology & University of Missouri–Kansas City.

Quantum-dot/dopamine bioconjugates function as redox coupled assemblies for in vitro and intracellular pH sensing.

Abstract: The use of semiconductor quantum dots (QDs) for bioimaging and sensing has progressively matured over the past decade. QDs are highly sensitive to charge-transfer processes, which can alter their optical properties. Here, we demonstrate that QD-dopamine-peptide bioconjugates can function as charge-transfer coupled pH sensors. Dopamine is normally characterized by two intrinsic redox properties: a Nernstian dependence of formal potential on pH and oxidation of hydroquinone to quinone by O(2) at basic pH. We show that the latter quinone can function as an electron acceptor quenching QD photoluminescence in a manner that depends directly on pH. We characterize the pH-dependent QD quenching using both electrochemistry and spectroscopy. QD-dopamine conjugates were also used as pH sensors that measured changes in cytoplasmic pH as cells underwent drug-induced alkalosis. A detailed mechanism describing the QD quenching processes that is consistent with dopamine's inherent redox chemistry is presented.

Subbandgap laser-induced single event effects: carrier generation via two-photon absorption

Abstract: Carrier generation based on subbandgap two-photon absorption is demonstrated and shown to be a viable alternative to the conventional single-photon excitation approach in laser-induced single event effects. The two-photon approach exhibits characteristics distinct from those of single-photon excitation, and may be advantageous for a range of single-event effect investigations. The charge track produced by two-photon absorption more closely resembles that of heavy-ion irradiation and, because the photon energy is subbandgap, backside injection through bulk silicon wafers is straightforward and three-dimensional mapping is possible.

Comparison of error rates in combinational and sequential logic

Abstract: A pulsed laser was used to demonstrate that, for transients much shorter than the clock period, error rates in sequential logic were independent of frequency, whereas error rates in combinational logic were linearly dependent on frequency. In addition, by measuring the error rate as a function of laser pulse energy for fixed clock frequency, the logarithmic dependence of the SEU vulnerable time period prior to the clock edge in combinational logic was established. A mixed mode circuit simulator program was used to successfully model the dynamic response of the logic circuit to pulses of laser light.

Critical evaluation of the pulsed laser method for single event effects testing and fundamental studies

Abstract: In this paper we present an evaluation of the pulsed laser as a technique for single events effects (SEE) testing. We explore in detail the important optical effects, such as laser beam propagation, surface reflection, and linear and nonlinear absorption, which determine the nature of laser-generated charge tracks in semiconductor materials. While there are differences in the structure of laser- and ion-generated charge tracks, we show that in many cases the pulsed laser remains an invaluable tool for SEE testing. Indeed, for several SEE applications, we show that the pulsed laser method represents a more practical approach than conventional accelerator-based methods. >

Intermolecular vibrational coherence in molecular liquids

Abstract: The femtosecond optical heterodyne detected optical Kerr effect/Raman-induced Kerr effect (OHD OKE/RIKE) is described in detail with emphasis on the utility for investigating the intermolecular spectra and dynamics of liquids. The femtosecond dynamics of the liquids CS2, benzene and CCI4 are addressed through a combination of conventional time-domain kinetic and Fourier-transform analyses, and the physical origin of the intermolecular intensity is addressed for each. The distinctions between the excitation mechanisms of the femtosecond OKE/RIKE and other continuous-wave and picosecond Raman techniques are described. The distinctions between the dephasing mechanisms of intramolecular and intermolecular vibrational modes are discussed.

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Determining the size and shape dependence of gold nanoparticle uptake into mammalian cells.

Abstract: We investigated the intracellular uptake of different sized and shaped colloidal gold nanoparticles. We showed that kinetics and saturation concentrations are highly dependent upon the physical dimensions of the nanoparticles (e.g., uptake half-life of 14, 50, and 74 nm nanoparticles is 2.10, 1.90, and 2.24 h, respectively). The findings from this study will have implications in the chemical design of nanostructures for biomedical applications (e.g., tuning intracellular delivery rates and amounts by nanoscale dimensions and engineering complex, multifunctional nanostructures for imaging and therapeutics).

Quantum dots versus organic dyes as fluorescent labels

Abstract: Suitable labels are at the core of Luminescence and fluorescence imaging and sensing. One of the most exciting, yet also controversial, advances in label technology is the emerging development of quantum dots (QDs)--inorganic nanocrystals with unique optical and chemical properties but complicated surface chemistry--as in vitro and in vivo fluorophores. Here we compare and evaluate the differences in physicochemical properties of common fluorescent labels, focusing on traditional organic dyes and QDs. Our aim is to provide a better understanding of the advantages and limitations of both classes of chromophores, to facilitate label choice and to address future challenges in the rational design and manipulation of QD labels.

Principles Of Fluorescence Spectroscopy

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The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

Abstract: 3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906