The use of near-infrared or infrared photons is a promising approach for biomedical imaging in living tissue. This technology often requires exogenous contrast agents with combinations of hydrodynamic diameter, absorption, quantum yield and stability that are not possible with conventional organic fluorophores. Here we show that the fluorescence emission of type II quantum dots can be tuned into the near infrared while preserving absorption cross-section, and that a polydentate phosphine coating renders them soluble, disperse and stable in serum. We then demonstrate that these quantum dots allow a major cancer surgery, sentinel lymph node mapping, to be performed in large animals under complete image guidance. Injection of only 400 pmol of near-infrared quantum dots permits sentinel lymph nodes 1 cm deep to be imaged easily in real time using excitation fluence rates of only 5 mW/cm(2). Taken together, the chemical, optical and in vivo data presented in this study demonstrate the potential of near-infrared quantum dots for biomedical imaging.

Near-infrared fluorescent type II quantum dots for sentinel lymph node mapping

This review focuses on key aspects of the thermal decomposition of multinary or mixed hydride materials, with a particular emphasis on the rational control and chemical tuning of the strategically important thermal decomposition temperature of such hydrides, Tdec. An attempt is also made to predict the thermal stability of as-yet unknown, elusive or even unknown hydrides. The future of a particularly promising class of materials for hydrogen storage, namely the catalytically enhanced complex metal hydrides, is discussed. The predictions are supported by thermodynamics considerations, calculations derived from molecular orbital (MO) theory and backed up by simple chemical insights and intuition.

Thermal decomposition of the non-interstitial hydrides for the storage and production of hydrogen.

We present a scalable wet chemical synthesis for a catalytically active nanostructured amorphous molybdenum sulfide material. The catalyst film is one of the most active nonprecious metal materials for electrochemical hydrogen evolution, drawing 10 mA/cm2 at ∼200 mV overpotential. To identify the active phase of the material, we perform X-ray photoelectron spectroscopy after testing under a variety of conditions. As deposited, the catalyst resembles amorphous MoS3, but domains resembling MoS2 in composition and chemical state are created under reaction conditions and may contribute to this material’s high electrochemical activity. The activity scales with electrochemically active surface area, suggesting that the rough, nanostructured catalyst morphology also contributes substantially to the film’s high activity. Electrochemical stability tests indicate that the catalyst remains highly active throughout prolonged operation. The overpotential required to attain a current density of 10 mA/cm2 increases by o...

Amorphous Molybdenum Sulfide Catalysts for Electrochemical Hydrogen Production: Insights into the Origin of their Catalytic Activity

3.1. Fundamental Characterization 6672 3.2. Photocurrent Action Spectroscopy 6673 3.3. Optical Characterization 6673 3.4. Characterization of Electron Transfer 6673 4. Electron Transport in Metal Oxide Films 6674 4.1. Mechanism of Photoinduced Carrier Transport 6674 4.2. Characterization of Diffusion Length 6675 4.3. One-Dimensional (1-D) Transport Architectures 6675 4.4. Electrolyte Interactions 6676 5. Recent Trends in Liquid-Junction Solar Cells 6676 5.1. Dye Sensitized Solar Cells 6677 5.2. Quantum Dot Sensitized Solar Cells 6678 5.3. Carbon Nanostructure Based Photochemical Solar Cells 6679

Beyond Photovoltaics: Semiconductor Nanoarchitectures for Liquid-Junction Solar Cells

Synthesis, structure, and bonding in polyiodide and metal iodide-iodine systems.

The donor properties of simple ethers—II[1]: Complexes of manganese(II), iron(II), cobalt(II) and nickel(II) halides with tetrahydrofuran and 1,2-dimethoxyethane

Mo K-edge EXAFS and S K-edge absorption studies of the amorphous molybdenum sulfides MoS4.7, MoS3, and MoS3.cntdot.nH2O (n .apprx. 2)

Organometallic precursors to the formation of GaN by MOCVD: structural characterisation of Me3Ga · NH3 by gas-phase electron diffraction

The reaction of Ga(CH3)3 with an excess of ammonia leads to the formation of (CH3)3Ga·NH3, which, when heated at 120 °C under 450 Torr nitrogen, decomposes to yield CH4 and the trimer [(CH3)2GaNH2]31 and not, as previously stated, a dimeric species. A single-crystal X-ray study of 1 revealed that it is a molecular species containing a (GaN)3 ring [Ga–N 1.93(2)–2.05(2)A] in which four consecutive ring atoms are coplanar. The remaining two atoms of the ring are on the same side of the plane so the ring has the sofa conformation. The internal ring angles range from 93.8(8) to 101.3(8)°(for N–Ga–N) and 119.5(9) to 125.3(9)°(for Ga–N–Ga). Compound 1 is monoclinic, space group P21/c, Z= 4. 985 Independent reflections have been measured on a diffractometer and the structure refined to R= 0.076. Spectroscopic evidence shows that 1 retains its trimeric nature in the gas phase. Thus, in the mass spectrum the parent ion is seen, while infrared spectra of mulls of solid 1, of gaseous 1 condensed onto CsI windows and of matrix-isolated 1 are in agreement with the same species being in both solid and gas phases.

Organometallic precursors for the formation of GaN by metal-organic chemical vapour deposition: a study of [(CH3)2GaNH2]3

The growth of thin layers of the transition metal sulfides Cr2S3, α-MnS and FeS by Chemical Vapour Deposition (CVD) is reported. Layers of Cr2S3 in the rhombohedral or trigonal form have been grown onto Pyrex, molybdenum or aluminium substrates using the single-source precursor Cr(S2CN(C2H5)2)3 in a low-pressure flow reactor. The temperature of the precursor was held at 255 °C and the substrate was heated to 450 °C for these experiments. The nature of the layer formed was determined by a combination of EDX analysis and glancing angle XRD. Growth rates up to 10 µm h−1 were achieved. In a separate series of experiments thin layers of α-MnS and FeS have been grown onto Pyrex substrates using propylene sulfide (C3H6S) as the sulfur source and CpMn(CO)3
(Cp = η-C5H5) or Cp2Fe as the metal source using a CVD reactor under a flow of nitrogen gas. An approximately 1∶1 molar ratio of C3H6S and CpMn(CO)3 and a substrate temperature of 410 °C gave a growth rate of α-MnS of some 4 µm h−1 and a crystalline layer as shown by EDX analysis and powder XRD. However, increasing the flow rate of the sulfur source or decreasing that of the metal source gave rise to sulfur-rich layers. Layers of FeS were grown on Pyrex substrates from C3H6S and Cp2Fe with a molar ratio of reactants of 1∶3 or higher and a substrate temperature of 410 °C. A growth rate of around 2.5 µm h−1 was achieved.

David A. Rice

Papers

The donor properties of simple ethers—II[1]: Complexes of manganese(II), iron(II), cobalt(II) and nickel(II) halides with tetrahydrofuran and 1,2-dimethoxyethane

Mo K-edge EXAFS and S K-edge absorption studies of the amorphous molybdenum sulfides MoS4.7, MoS3, and MoS3.cntdot.nH2O (n .apprx. 2)

Organometallic precursors to the formation of GaN by MOCVD: structural characterisation of Me3Ga · NH3 by gas-phase electron diffraction

Organometallic precursors for the formation of GaN by metal-organic chemical vapour deposition: a study of [(CH3)2GaNH2]3

Growth of thin layers of metal sulfides by chemical vapour deposition using dual source and single source precursors: routes to Cr2S3, α-MnS and FeS